Sifrei Bamidbar 152

(Bamidbar 29:39) "These shall you offer to the L-rd on your festivals, aside from, etc.": These are the vows and the gift-offerings that he vows on the festival, that he is to bring them on the festival. You say this, but perhaps Scripture speaks of the vows and the thank-offerings of the whole year? (This is not so, for Devarim 12:5-6) "And you shall come there and you shall bring there … your vows and your gifts" already speaks of the vows and gifts of the whole year. How, then, am I to understand "These shall you offer to the L-rd on your festivals"? As referring to the vows and the gift-offerings that he vows on the festival, that they are to be brought on the festival. "aside from your vows" These are the bird-pairs of the zavim and the zavoth (those with a genital flow), which (bird-pairs) the Torah permitted to be brought on a festival. "aside from your vows … (31) And Moses said to the children of Israel": (The purpose of "And Moses said" is) to conclude the foregoing. For if I read "aside from your vows … (30:2) And Moses spoke," I would not know to what it ("And Moses spoke") referred, (to what precedes or to what follows?) It is, therefore, written "from your vows … And Moses said," to conclude what precedes. These are the words of R. Yishmael.