Reference for Chullin 126:5

אמר אביי

For should you say that they are two distinct birds then consider this: seeing that the purport of Deuteronomy is to add to the laws, why is it that here [in Leviticus] the words 'after its kind' are appended to the ayyah but there [in Deuteronomy] these words are appended to the dayyah?

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