Hadith 10:672
Abu Bakr narrated to us, he said: Mu’adh ibn Mu’adh narrated to us, from Ash’ath, from al-Hasan, that he said regarding a man who said to his wife, "If you become pregnant, then you are divorced": He said, "He should have intercourse with her, and when she becomes pure from menstruation, then he should withhold from her until the like of that." And Ibn Sirin said: "He should have intercourse with her until she becomes pregnant."
حدثنا أبو بكر قال نا معاذ بن معاذ عن أشعث عن الحسن أنه قال في رجل قال لامرأته إذا حملت فأنت طالق قال يغشاها فإذا تطهرت من الحيض ثم يمسكها عنها إلى مثل ذلك وقال بن سيرين يغشاها حتى تحمل