Reference for Bekhorot 91:20

בכור לנחלה ולכהן שנאמר

EVEN IF SHE HAD GIVEN BIRTH WHEN SHE WAS A BONDWOMAN, BUT IS FREE [NOW], OR [HAD BORNE A CHILD] WHEN SHE WAS A HEATHEN BUT HAS SINCE BECOME A PROSELYTE IF AFTER COMING TO THE ISRAELITE SHE BEARS TO HIM, [THE INFANT] IS ALSO CONSIDERED A FIRST-BORN [WITH RESPECT] TO INHERITANCE BUT NOT A FIRST-BORN TO REDEMPTION FROM A PRIEST.<span class="x" onmousemove="('comment',' Since he did not have children previously, the present infant is a first-born as regards inheritance, but is not a first-born to be released by redemption. as the Hebrew woman, the gentile woman and the maid-servant have already had children.');">¹⁵</span>

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