Numbers 18:18

כחזה התנופה וכשוק הימין [AND THE FLESH OF THEM (of the firstborn animals) SHALL BE TO YOU] AS THE WAVE BREAST AND THE RIGHT SHOULDER of the festival offerings which may be eaten by the priests, their wives and their sons and men-servants during a period of two days and one (the intervening) night, reckoning from the day of slaughtering; so, too, the flesh of the firstborn animal sacrifice may be eaten during two days and one night (Sifrei Bamidbar 118; Zevachim 57a). לך יהיה IT SHALL BE THINE — Rabbi Akiba came and taught: By repeating the words לך יהיה Scripture adds another “status” (more lit., state of being; i.e., it intends the status implied in the first לך יהיה to be extended), in order that you should not say that it shall be to them even as the breast and shoulder of the thanksgiving offering, which may only be eaten during one day and the following night (Sifrei Bamidbar 118; Zevachim 57a).

וּבְשָׂרָ֖ם יִהְיֶה־לָּ֑ךְ כַּחֲזֵ֧ה הַתְּנוּפָ֛ה וּכְשׁ֥וֹק הַיָּמִ֖ין לְךָ֥ יִהְיֶֽה׃

And the flesh of them shall be thine, as the wave breast and as the right shoulder shall they be thine.