Mishkat al-Masabih 13 Marriage كتاب النكاح 250

وَعَنْ سَعِيدِ بْنِ الْمُسَيَّبِ قَالَ: قَالَ عُمَرُ بْنُ الْخَطَّابِ رَضِيَ اللَّهُ عَنْهُ أَيُّمَا امْرَأَةٍ طُلِّقَتْ فَحَاضَتْ حَيْضَةً أَوْ حَيْضَتَيْنِ ثُمَّ رُفِعَتْهَا حيضتُها فإنَّها تنتظِرُ تسعةَ أشهرٍ فإنْ بانَ لَهَا حَمْلٌ فَذَلِكَ وَإِلَّا اعْتَدَّتْ بَعْدَ التِّسْعَةِ الْأَشْهَرِ ثلاثةَ أشهرٍ ثمَّ حلَّتْ. رَوَاهُ مَالك

Sa’id b. al-Musayyib reported ‘Umar b. al-Khattab as saying, “If any woman is divorced and has one or two menstrual periods then stops menstruating she must wait nine months, and if it is apparent that she is pregnant the rules concerning that are applied; otherwise she must observe a period of three months after the nine months are ended, after which she may lawfully remarry. Malik transmitted it.