Musnad Abu Ya'la al-Mawsili 2:33

Abu Kurayb narrated to us, Yunus bin Bukayr narrated to us, from al-A’mash, from Abu Salih, from Ibn Umar, who said: Umar entered upon Hafsa while she was weeping. He said to her, "What makes you weep? Perhaps the Messenger of Allah (may Allah bless him and grant him peace) has divorced you. He had indeed divorced you once, then took you back for my sake. By Allah, if he divorces you another time, I will never speak to you again."