Gemara

(Rav): One may wash his hands in the morning and stipulate that he will guard their Taharah the entire day (so he may eat without washing again).

In a certain valley, water was scarce. R. Avina allowed the residents to wash in the morning, and stipulate that this will suffice for all meals that day.

Some say that he permits only in pressed circumstances, unlike Rav. Some say that he always permits, like Rav.

Berachos 42a (R. Chiya bar Ashi): Shechitah must be Tekef to Semichah, Tefilah (Shemoneh Esre) must be Tekef to Ge'ulah (Ga'al Yisrael), and Berachah must be Tekef to washing.

Pesachim 106a (Rav Berona and Rav Ada bar Ahavah citing Rav): One who washed his hands should not say Kidush (it is a Hefsek (interruption) between washing and ha'Motzi. Rather, he hears Kidush from someone else.)

Rav Yitzchak bar Shmuel: Rav is still alive, and you already forgot his teachings!

When Rav preferred bread, he was Mekadesh on bread. When he preferred wine, he was Mekadesh on wine.

115a (Rav Chisda): (Even though) one washed his hands for the first dipping (at the Seder), he washes for the second dipping.

Question: Why must he wash again? He already washed (knowing that he will dip again)!

Answer: Since we say Hagadah and Hallel in between, perhaps he was distracted and touched (something that is Metamei the hands).

Rishonim

Rif (Pesachim 22a): We learn from Rav Yitzchak (bar Shmuel) that one says Kidush on what he prefers, whether or not he washed. This is the Halachah.

Ran (DH Natal): The Rif explains that if one washed, he does not say Kidush because (since we do not wash for Peros,) he showed that he prefers bread. Rav Berona never permits Kidush on bread. He should not say Kidush on wine, for it is not dear to him. This is rejected, for whenever Rav preferred bread, he was Mekadesh on bread. However, we did not refute Rav Berona's inference that washing first shows that he prefers bread. Therefore, he says Kidush only on bread. The Rambam holds like this. The Rashbam explains Rav Berona to teach that he does not say Kidush, to avoid Hesech ha'Da'as that would obligate washing again. This is rejected, for sometimes Rav was Mekadesh on bread. Surely, he washed beforehand! This shows that Kidush is not a Hefsek. However, l'Chatchilah we say Kidush and then wash, like Beis Hillel (Berachos 52b), who say to mix the cup and then wash, for one must eat Tekef to washing.

Ba'al ha'Ma'or (21b DH Amar): Rav holds that one who tasted may not say Kidush. Also one who washed showed that he is hasty to eat and scorns Kidush. It is as if he tasted, so he does not say Kidush. Rather, others are Mekadesh for him. Rav Yitzchak rejected this. Since one can be Mekadesh on bread, he did not scorn Kidush. He is Mekadesh on whichever he prefers. We hold that even one who tasted says Kidush, so all the more so we are not concerned for Rav Berona's opinion.

Rambam (Hilchos Shabbos 29:6): One does not wash until after Kidush.

Rambam (9): If one desired bread more than wine, or he did not have wine, he washes first, says ha'Motzi, says Kidush, and then cuts the bread and eats.

Rambam (10): If one intended to say Kidush on wine, but forgot and washed before Kidush, he says Kidush on bread, and not on wine, since he washed for the meal.

Mordechai (Pesachim 611, page 37a, middle of second column): Rashi says that one who washed his hands should not say Kidush, for if so he would need to wash again to eat, since Kidush is Hesech ha'Da'as (his mind was diverted). Rather, he hears it from one who did not wash. Why didn't Rav Berona forbid washing before Kidush? It is because this is not always true. One may wash if he will not say Kidush (rather, hear it). Why didn't Rav Berona say that if one washed and said Kidush, he must wash again? This would connote that one may do so. Really, it is improper, for his first Berachah was l'Vatalah. One may wash in the morning and stipulate that this washing helps (for all meals) for the entire day (Chulin 106b). If so, why is Kidush Hesech ha'Da'as? This is the ultimate Tanai (stipulation), since he intends to eat immediately! Rather, a Tanai helps only in the morning, when it is normal to stipulate. Also, we can say that a Tanai helps only if he does not have water nearby. Rav clearly permits even when water is available, i.e. there is water in the region, but it is not near him, and he must pursue it, or he needs the water for something else. Here, he has much water in his house, so a Tanai does not help. R. Elchanan says that one who washed may not say Kidush because it looks like he washes for Peros, which is called haughtiness (106a). This resolves everything. The Halachah does not follow this opinion (Rav Yitzchak refuted it), so one may wash before Kidush. It is not Hesech ha'Da'as. On Pesach, there is a big delay, so the Ba'al ha'Bayis should not wash before Kidush, for he must wash again before dipping, so his first Berachah would be l'Vatalah. The others may wash before Kidush. For them it is not Hesech ha'Da'as. They need not wash again for the dipping, just like Rav Berona held, that Kidush is a Hefsek only for the one who says it.

Beis Yosef (OC 473 DH v'Ein): Why is there is a bigger Hefsek in the Kidush of Pesach than in Kidush of any other Shabbos or Yom Tov? If it is because he must say (Berachos on) wine, Kidush, Ner, Havdalah and Shehecheyanu, this is only when Pesach is on Motza'ei Shabbos. How can he explain when it is on another night? Also, why must he wash again for the dipping? It should help for the dipping, just like washing before Kidush helps for eating (bread) on Shabbos and (any other) Yom Tov! This requires investigation.

Bigdei Yesha (on Mordechai, 115): Surely, on Pesach there is a big Hefsek between Kidush and the meal, i.e. the Hagadah!

Mordechai (ibid.): Rav Yitzchak explains that sometimes Rav was Mekadesh on bread, and sometimes on wine. In both cases he washed before Kidush, and did not wash again afterwards, for Kidush is not a Hefsek. (Rashbam Pesachim 106b DH d'Chaviva explains like this.) I distinguish them. Rav washed before Kidush only when saying Kidush over bread. R. Tam says that he always said Kidush on wine, just sometimes he wanted to eat immediately afterwards, without washing in between. We hold that Kidush is not a Hefsek, since he intends to eat immediately. For the same reason, Havdalah is not a Hefsek. Do not say that only Kidush is not a Hefsek, for it is like part of the meal. Rav holds that Kidush is not a Hefsek, even though he holds that Kidush need not be where the meal is! The same applies for us, regarding Havdalah.

Poskim

Shulchan Aruch (OC 166:1): Some say that one need not be careful about a Hefsek (interruption) between Netilas Yadayim and ha'Motzi. Some say that one must be careful. It is good to be careful.

Beis Yosef (DH Garsinan): In Pesachim we require washing again for the second dipping. Since we say Hagadah and Hallel in between, perhaps he was distracted and touched. If one his hands before Kidush, Kidush is not considered a Hefsek! There, it is because he intends to eat.

Shulchan Aruch (271:12): After Kidush over wine, he washes his hands. If he washed before Kidush, he showed that he prefers bread, so he does not say Kidush over wine, rather, over bread.

Beis Yosef (DH v'Chasav): The Tur says that the Rosh would wash before Kidush. He challenged this, for if so we cannot explain Rav Berona simply, i.e. like the Ran, that it depends on Kidush. According to R. Tam and the Rashbam, it is due to Hesech ha'Da'as. However, in Siman 289 the Tur explains Rav Berona's law due to Hesech ha'Da'as. All the Poskim except for R. Yonah rule unlike Rav Berona.

Beis Yosef (DH v'Af): Even though the Tur questioned the Rosh, I saw many do like the Rosh. This was the custom in Sefard. I questioned this. The Rif and his followers require Kidush before Netilah. If he washed first, he does not say Kidush on wine. The Rashbam holds that it is better to say Kidush first. The Ba'al ha'Ma'or did not specify. Presumably, he explains the Mishnah simply, like the Rashbam. R. Tam and the Ri disagree only because they forbid Kidush on bread. We permit, so there is no proof from Rav Yitzchak that one must wash first. Even according to them, the Tur said only that one may wash first, but not that one must. Why is the custom unlike all these Rishonim? Even R. Tam and the Ri permit to say Kidush first! Perhaps the Rosh washed first only occasionally. Hagahos Maimoniyos (29:100) says 'nowadays the custom is to wash first, like the Rashbam and Tosfos.' He must mean that sometimes people wash first and even so they say Kidush, for the Rashbam says that it is better to say Kidush first!

Note: If there are strong reasons to prefer washing after Kidush, why is the custom (and the Rosh's practice) to sometimes wash first? The Rashba (1:752) says that everyone washes before Kidush. Hagahos Maimoniyos (29:8) says that the Rashbam permits washing first b'Di'eved, and cites others who permit l'Chatchilah. Why would he attribute the custom to the Rashbam? Hagahos Maimoniyos (100) explained why we cover the bread. Since we wash before Kidush, if the bread were exposed we would need to bless on it before wine. It would be logical to say that he cited the Rashbam to teach that if the bread were exposed, even the Rashbam would obligate saying Kidush on it, since it is not a Hefsek. However, his words connote otherwise (unless one rearranges them).

Taz (14): The Gemara concludes like Rav Yitzchak. Why did Rav Amram (cited in the Tur) bring Rav Berona? He holds that Rav Berona was only partially rejected. Rav Berona holds that one who washed may not say any Kidush. Rav Yitzchak holds that he may not say Kidush on wine, rather, on bread. We hold like Rav Berona, that he does not say Kidush on wine. The other Perushim permit l'Chatchilah to wash first. They were forced to say that Rav Berona holds that Kidush need not be where one eats. The Tur questioned why the Rosh did not follow Rav Amram and the Rambam l'Chatchilah, who need not say so to explain Rav Berona. Why should he do what Rav Berona disqualifies even b'Di'eved? Even though the Rema wrote '(one should wash first;) one should not deviate', I say that we do not discourage one who wants to do like the first opinion; it is proper to do so.

Gra (30): The first opinion is primary.

Mishnah Berurah (58): The first opinion holds that the Mekadesh washes after Kidush, to avoid a Hefsek, but his household, who are Yotzei through him, may wash before Kidush.

Magen Avraham (27): According to the opinion (in OC 166:1) that forbids a Hefsek between Netilas Yadayim and eating, one may not even pour wine into the cup in between.

Mishnah Berurah (59): We are concerned for what he prefers only in this case, that he washed and there is also concern for a Hefsek. If he did not wash, he may be Mekadesh on wine even if he prefers bread. See what I wrote below (272:32).

Mishnah Berurah (272:32): When there is wine in the city, we are concerned for R. Tam's opinion that one may not be Mekadesh on bread. We hold like the Rosh and others who permit Kidush on bread, but this is only if he prefers bread. Perhaps people rely on this to be lenient.

Mishnah Berurah (60): When one has no wine, he must wash first and say Kidush on bread. The Rema holds that therefore, it is good to be consistent, and always wash first.

Kaf ha'Chayim (76,79): The Ari Zal holds that one must say Kidush first, for it completes Ma'ariv. Washing pertains to the meal. This applies also to those who are Yotzei through another's Kidush.

Kaf ha'Chayim (166:2): Also the day Kidush must be before Netilas Yadayim.

Kaf ha'Chayim (77): If one washed but did not yet bless Al Netilas Yadayim, he says Kidush, then washes again with a Berachah. Even if he blessed, he should say Kidush on the wine, for Al Pi Kabalah one should not omit this, and some Poskim permit this l'Chatchilah.

Rema: Some say that l'Chatchilah he should wash before Kidush (and say Kidush on wine). This is the custom. One should not deviate, except for on Pesach.

Mishnah Berurah (62): Several Acharonim say that it is better to say Kidush on wine before washing. Then letter of the law he is Yotzei according to all opinions. Many places follow them. However, if he already washed, he does like the Rema says.

Taz (15): On Pesach, there is a long delay for the Hagadah (before the meal), so all agree that one should not wash before Kidush.

Gra (30): Also, on Pesach one may not say Kidush on bread, so washing beforehand looks like he scorns Kidush.