Reference for Temurah 36:38

תמורת עולה ולד תמורה ולד ולד ולדה עד סוף כל העולם הרי אלו כעולה וטעונין הפשט וניתוח וכליל לאשים

Whence do we include [for offering] the case of the young [of a thanksgiving offering], exchanges and substitutions?<span class="x" onmousemove="('comment',' Where the thanksgiving offering became lost and he set aside another in its place. Tosaf. observes that this is exactly the case mentioned above: If one sets aside a thanksgiving offering, etc. Wilna Gaon, however, adds that substitutions are included for offering even after the sacrificing of the first animal.');">²⁶</span>

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