Why does the Torah insert the Mitzvah of Bikurim here?
Rashi: Still with reference to Pasuk 11, the Torah is teaching us that Bikurim applies even during the Shemitah.
Rashbam: When you go to the Beis Hamikdash for Aliyah l'Regel, make use of the opportunity and take your Bikurim 1 with you.
What are the connotations of "Reishis"?
Rashi: The Mitzvah applies to the first fruit that ripens on the tree.
Seforno: It means that Bikurim should be given from the best 1 of the first fruit to appear.
To which Peros does Bikurim pertain?
Rashi: It pertains to the seven Peros listed in Devarim 8:8 - wheat, barley, grapes, figs and pomegranates, olives and dates.
What does the Mitzvah of Bikurim entail?
Rashi: When one sees a fig (for example) that has ripened, one ties a red thread around it and declares it Bikurim. When one subsequently goes to Yerushalayim, one takes it with him and gives it to a Kohen.
What are the connotations of the Lav "Lo Sevashel Gedi ba'Chalev Imo"?
Targum Onkelos: It is a prohibition against eating meat and milk.
Targum Yonasan: It is a prohibition against cooking and eating meat mixed with milk. 3
Moshav Zekenim: It is forbidden only if they were cooked together, but not if they were soaked together the entire day. 4
Hadar Zekenim #1: Do not delay [offering Bechoros] for them to nurse and mature; offer them immediately.
Hadar Zekenim citing Sefer ha'Gan: It is cruelty to cook meat with the milk from which it grew and lived. The Torah similarly forbids taking a mother bird with its young, and to slaughter a mother and her child on the same day.
Hadar Zekenim #2: Do not delay Bikurim to nurture on the tree, which is their 'mother'. Rather, bring them immediately. 'Gedi' is like 'mi'Meged'; or, it is anything soft.
Hadar Zekenim #3: If you bring Bikurim, the grain will not burn when it is soft and in Chelev ha'Aretz (its mother); if not they will burn then. Do not bring Bikurim when they are soft; wait for them to ripen.
Da'as Zekenim (34:26): This hints to the Isur [mid'Rabanan] to marry a woman nursing another man's baby, until 24 months. Rosh citing R. Sadya Gaon - the Gematriya of Tevashel is 730 (the number of days in two years; the Beis hints to) excluding the day of death 5 [of the father] and the day he is Mekadesh her.
The Isur actually extends to cooking it in any milk.
Riva: In Devarim (14:21), Rashi said that the three times exclude meat of Chayos, birds and Tamei animals.
Because if one does, it will arouse Hashem's anger, and He will be Mevashel (ripen) the grain mixed together with the stubble (See Na'ar Yonasan).
Moshav Zekenim: R"T inferred that absorptions occur through prolonged soaking. If not, what is the Chidush? Some reject this. The Chidush is if they were soaked together the entire day in a Kli Sheni that was Yad Soledes Bo.
The father's death is irrelevant! Also if he is alive (e.g. he divorced the mother), the baby should nurse for 24 months! Surely the text should say 'the day of birth', like in Kitzur Piskei ha'Rosh (Yevamos 4:26). The scribe confused this with the Isur of marrying a widow within three months; there, we exclude the day of death and the day of Kidushin. (PF)
Why does the Torah write specifically "Gedi"?
Rashi #1: Because 'Gedi' is the term that incorporates all young, tender animals. 1
Rashi (in Devarim 14:21): It writes "Gedi" three times, to preclude Chayos, birds and fish from the prohibition.
Rashbam: Because it was common to cook a kid-goat in its mother's milk. This is disgraceful and gluttony 2
Ibn Ezra: It was common to cook a kid-goat in milk, for its meat is not moist.
Why does the Torah insert meat and milk here, in connection with the festivals?
Rashbam: Because one tends to eat many animals on the festivals.
What is the connection between Bikurim and meat and milk?
Seforno: To teach us that, if one wants to enjoy a successful fruit harvest, the way to do it is by observing the Mitzvah of Bikurim (and Terumah), as the Pasuk writes in Yechezkel, 44:30, and not by indulging in various kinds of sorcery, such as cooking kid-goats in their mothers' milk.
Hadar Zekenim: Refer to 23:19:5:5,7,8.
Moshav Zekenim (34:26): Hashem commanded us to separate Bikurim, and forbade to us new grain until we bring the Omer and separate [its Kometz], so you must separate milk from meat, and while they are together, they are forbidden.
Rashi writes that meat and milk is written three times; one time forbids eating meat cooked in milk. We should know this already from "Lo Sochal Kol To'evah"!
Riva citing R. Elyakim: "Lo Sochal Kol To'evah" is Lav shebi'Chlalos (forbids many matters), so I would not lash due to it. Our verse obligates lashes for eating it.