Reference for Chullin 281:33

כיון דאסור בתשמיש המטה ליתי עשה דידיה ולידחי עשה דשלוח הקן קמ"ל:

Great is the peace between man and wife, for the Torah has permitted the name of the Holy One, blessed be He, which is to be written in all sanctity, to be washed away in the waters of bitterness,<span class="x" onmousemove="('comment',' Cf. Num. V, 23.');"><sup>25</sup></span>