Reference for Chullin 44:5

שיכול והלא דין הוא

But I will now say that pigeons, inasmuch as in the Divine Law they are always preceded by the epithet 'young', are qualified for sacrifice only when small, and not when fully grown; whereas turtle doves [I submit] may be offered either when fully grown or even when small! - [Turtle doves must be placed under conditions] similar to pigeons; thus, just as pigeons are qualified [for sacrifice] only when small and not when fully grown, so turtle doves are qualified [for sacrifice] only when fully grown and not when small.<span class="x" onmousemove="('comment',' The conditions are that in each kind there shall obtain a qualifying as well as a disqualifying age. in');">²</span>

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