Commento su Deuteronomio 15:20

לפני ה׳ אלהיך תאכלנה THOU SHALT EAT IT BEFORE THE LORD THY GOD — Scripture is speaking to the priest (not to the owner to whom תקדיש in the previous verse refers), for we find already stated that it (the בכור) is one of the dues of the priests whether it is unblemished (and its blood and fat portions are to be sacrificed on the altar and the flesh eaten by the priests), or whether it is blemished (when it must not be offered on the altar), for it states, (Numbers 18:18) “and the flesh of them (the firstborn animals, both the blemished and the unblemished) shall be thine” (the priest’s) (cf. Bekhorot 28a).

בשעריך) תאכלנו), “you may consume it in your cities.” The Torah refers to people who are authorized to eat it (priests).
שנה בשנה, “year by year;” this does not mean that it is forbidden to eat it after it has attained its first birthday as it has been compared elsewhere to the second tithe (Deut. 14,23), but it means that preferably it is to be eaten before it has attained its first birthday.
אתה וביתך, “you and your house,” i.e. the household of the priest.

Just as the second tithe is not disqualified from one year to the next, etc. As it is written regarding the tithes (above 14:28), “At the end of three years, separate all the tithes of your produce,” and Rashi explains, “This comes to teach that if one withheld his tithes, etc.”