Reference for Sanhedrin 216:18
(בראשית ח, יט) למשפחותיהם יצאו מן התיבה א"ר יוחנן למשפחותם ולא הם
Whereon R. Johanan observed: From this we deduce that cohabitation had been forbidden.<span class="x" onmousemove="('comment',' Since it is obvious that Noah's wife etc., were to leave the ark with him, the verse must be explained as granting permission for the resumption of marital ties. Hence these were interdicted in the ark. ');"><sup>33</sup></span> Our Rabbis taught: Three copulated in the ark, and they were all punished — the dog, the raven, and Ham. The dog was doomed to be tied, the raven expectorates [his seed into his mate's mouth]. and Ham was smitten in his skin.<span class="x" onmousemove="('comment',' I.e., from him descended Cush (the negro) who is black-skinned. ');"><sup>34</sup></span>