Reference for Nedarim 37:3

ותני עלה ואסורים בגיזה ועבודה

whether clean or unclean — the claimant must furnish proof [that they are first-borns].<span class="x" onmousemove="('comment',' I.e., if the priest claims the firstling or redemption money for the first-born. ');">³</span>

Jastrow

Jastrow

Jastrow