Yosef Karo, Translation:Shulchan Aruch — Yoreh Deah 195…
“ If another person did not drink in between them, or he poured from one cup to another, even if he poured it back into the original cup. If she drank, and he didn't know and wants to drink from her cup, she does not need to tell him not to drink, and she can drink from his cup. And if she drank from a cup and left, there are those who say that he may drink the leftovers, since once she left, there is no desire. |dir="rtl" lang="he"| סעיף ד לא ישתה משיורי כוס ששתתה היא. ”
