Reference for Shevuot 35:11

אמר רבא זאת אומרת המשמש מת בעריות פטור דאי סלקא דעתך חייב הכא מאי טעמא פטור משום דאנוס הוא אי אנוס הוא כי פירש מיד נמי ניפטר אנוס הוא

- He said to him: If you have learnt [the Baraitha thus], it is defective, and your should read it thus: This is the negative precept concerning a menstruous woman for which one is liable; if [however] he was cohabiting with a clean woman, and she said to him; 'I have become unclean', and he withdrew immediately, he is liable: this is the positive precept concerning a menstruous woman, etc. The text says: 'If he withdrew immediately, he is liable.' What should he do? R'Huna said in the name of Rab: He should press his ten nails into the ground [i.e., bed] until his desire dies out.<span class="x" onmousemove="('comment',' He should remain passive.');">²⁶</span>

Jastrow