What does "Tzofnas Pane'ach" mean?
Rashi, Targum Onkelos and Targum Yonasan: It means 'the revealer of hidden things'. 1
Ha'Emek Davar: Pane'ach is from Pa, from the root Tofa'ah and honor, and Nach (pleasant and delight of the soul). Normally, one who lived years in lowliness and suddenly was raised to greatness, would go crazy or die. Pharaoh was impressed that Yosef was unchanged. Also, one who is used to slavery and submssiveness does not know how to conduct authority suddenly - and Yosef went to wondrous authority! Pharaoh concluded that Yosef was never a slave or lowly; his potential is to be a leader, just it was not realized until now. Tzofnas Pane'ach hints that was hidden in him the potential for authority and pleasantness.
See Ba'al ha'Turim. Although the Rashbam learns that it was an Egyptian name, according to the Ramban, Pharaoh called Yosef by a Kena'ani (Ivri) name in his honor - just like the daughter of Pharaoh would later call Moshe Rabeinu by a Hebrew name in his honor - See Ramban. Rashi, who comments that "Pa'ne'ach" has no sequel in Tanach, seems to concur with the latter explanation. Emes l'Yakov points out that every Egyptian name has two of the three letters "Pei-Reish-Ayin" in that order.
Why is the name "Tzofnas Pane'ach" not mentioned again?
Who was Osnas?
Targum Yonasan, Da'as Zekenim and Hadar Zekeinim (citing Pirkei d'R. Eliezer): She was the daughter of Dinah and Shechem. 1
Refer to 41:47:152:1.
Why did Pharaoh change Yosef's name?
Rashi (in Divrei Hayamim) and Rashbam: Because it was customary for kings (and other dignitaries) to change the name 1 of the person that they appointed to take charge of their household. 2
Perhaps we can also say that it was by Divine design, so that his brothers should not know the identity of the new viceroy. (EC)
Malbim: It was lest people complain that they are under a slave. His new name means 'the revealer of hidden things', i.e. the Ru'ach Elokim.
Rashi (in Divrei ha'Yamim 2, 36:4): To make it clear that they retained jurisdiction over them, to the point that they could even change their name at will.
As we find by Moshe and Yehoshu'a (Bamidbar 13:16) and by Nevuchdnetzar and Daniel (Daniel, 4:5).
Is "Poti Fera" the same as Potifar?
Rashi and Ramban: Originally, he was called Potifar. However, after purchasing the good-looking Yosef for immoral purposes, Hashem caused him to become castrated; 1 so his name was changed to Poti Fera. 2
Rashbam: Potifar and Poti Fera are two different people.
What was "On"?
Ramban: 'On' was probably the name of the idol that Poti Fera worshipped. 1
Rashbam: It was the name of the town of which Poti Fera was the mayor. 2
Why did Pharaoh marry off Yosef, and why to Poti Fera's daughter?
Oznayim la'Torah: For three possible reasons: (a) Because now that Yosef had married his daughter, Poti Fera (i.e. Potifar) would publicly dispel the notion that Yosef was a slave
See Oznayim la'Torah.
Why did Yosef, a king, marry a commoner's daughter?
Da'as Zekenim #1, Hadar Zekenim #1: Initially, Yosef was Potifar's slave. He thought, if I will not do his will and marry his daughter, he will disgrace me and inform that I was his slave. Rather, I will marry her, and he will honor me.
Da'as Zekenim #2, Hadar Zekenim #2: She was Dinah's daughter from Shechem. Yakov put an amulet around her neck and threw her underneath a bush, and miraculously she was brought to Egypt. Potifar raised her in his house, therefore she was called his daughter, just like we find that Moshe is called Bisyah's daughter, for she raised him. 1 Girls came to see Yosef, and threw ornaments to him. Osnas threw her amulet. Yosef realized that she descends from Yakov, and married her. 2
Redak (Divrei ha'Yamim 1:4:18, from Vayikra Rabah 1): Yered, Avigdor and Chever refer to Moshe. They are called Bnei Bisyah, for she raised him.
If so, why does it say that Pharaoh gave her to Yosef? Perhaps Pharaoh persuaded Potifar to agree to give her, even though this would imply that Yosef was innocent and his wife lied. (PF)
Why does it say "va'Yetzei Yosef Al Eretz Mitzrayim"? It says before that Pharaoh put him over all of Egypt!
Malbim: Before [his name was changed and he married Osnas], he was worried lest people rebel against him.
Ha'Emek Davar: He went to see the parts of every city, district and its people, and to appoint overseers, big and small, as he deemed proper. 1
Malbim (46): We learn this from verse 46 "va'Yetzei va'Ya'avor b'Chol Eretz Mitzrayim."
QUESTIONS ON RASHI
Rashi writes that Poti Fera is Potifar Why is he called here "Kohen (the priest of) On"? Earlier. he is called "Sar ha'Tabachim"!
Rashi (Bereishis 47:22): Although the word "Kohen" usually means a priest, sometimes it means a great man or a chief. 1
Ramban: Initially, Potifar was one of Pharaoh's chief officers. However, when he became castrated, he was so embarrassed that he resigned his post and became a priest 2 in a 'monastery', as was customary among important dignitaries.
Rashbam As the Navi (in Shmu'el 2, 8:18) writes "and the sons of David were 'Kohanim'
