Chullin 126
מכדי משנה תורה לאוסופי הוא דאתא מאי שנא הכא דכתיב דאה ומ"ש הכא דכתיב ראה ולא כתיב דאה
then consider this: seeing that the purport of Deuteronomy is to add to the laws, why is it that here [in Leviticus] it mentions the da'ah but there [in Deuteronomy] only the ra'ah and not the da'ah?
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?
כך איה ודיה אחת היא דאי ס"ד תרתי אינון מכדי משנה תורה לאוסופי הוא דאתא מאי שנא הכא דכתיב למינה אאיה ומ"ש התם דכתיב למינה אדיה
But since the ayyah and the dayyah are one and the same why are they both stated? - For the reason given in the following Baraitha: Rabbi says: It is sufficient when I read the ayyah, why then is the dayyah mentioned?
אלא ש"מ
So as not to give skeptics cause for criticism, for you might call it the ayyah and they the dayyah, or you the dayyah and they the ayyah; therefore it is written in Deuteronomy, The ra'ah, the ayyah and the dayyah after its kind.<a rel="footnote" href="#2"><sup>2</sup></a>
כדי שלא תתן פתחון פה לבעל דין לחלוק שלא תהא אתה קורא איה והוא קורא דיה אתה קורא דיה והוא קורא איה לכך כתב במשנה תורה
Now presumably, just as in the case of cattle a new species is added to the list, so too in the case of birds a new species is added!<a rel="footnote" href="#4"><sup>4</sup></a>
ראה זו איה ולמה נקרא שמה ראה שרואה ביותר וכן הוא אומר
But since [according to R'Abbahu] the ra'ah and the ayyah are one and the same, it would follow then that the da'ah is not the same as the ra'ah and [this being so] why is it that here [in Leviticus] the da'ah is mentioned but there [in Deuteronomy], the purport of which is to add to the laws, the da'ah is not mentioned?
תנא
But then since the ra'ah and the ayyah are one and the same, it would follow that the dayyah is not the same as the ayyah, and [this being so] why is it that here [in Leviticus] the words 'after its kind' are appended to the ayyah whereas there [in Deuteronomy] these words are not added to the ayyah but to the dayyah?
תניא איסי בן יהודה אומר
What is the point of this teaching? - It sets forth the idea, also expressed by R'Huna in the name of Rab (others say: R'Huna in the name of Rab on the authority of R'Meir) , viz. , A teacher should always teach his pupil succinctly.<a rel="footnote" href="#11"><sup>11</sup></a>
ת"ש דא"ר יוחנן
For since he (R. Abbahu) says that the ra'ah is identical with the ayyah, and in the conclusion he holds that all four - ayyah, dayyah, ra'ah and da'ah - are different names of one and the same bird, it is evident that according to him there are not twenty-four birds enumerated in the Torah. The argument in the Gemara at the outset presupposes the acceptance by R. Abbahu of R. Hisda's view, but the conclusion shows that he cannot agree with it.