Reference for Ketubot 205:6

א"ל רב עוירא מי דמי התם חד כריסא אית לה תרתי כריסתא לית לה הכא מצי א"ל טחון וזבין טחון ואותיב

Avira said to him: Are [the two cases] alike? There [the woman] has only one stomach, she does not have two stomachs; but here he might say to him, “Grind [in your own mill] and sell; grind [in mine] and keep.”

Jastrow