How a pregnant woman is to be divorced

It was narrated from Ibn 'Umar that:
he divorced his wife when she was menstruating, and 'Umar mentioned that to the Prophet ﷺ. He said: "Tell him to take her back then divorce her when she is pure (not menstruating) or pregnant."

حَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ، وَعَلِيُّ بْنُ مُحَمَّدٍ، قَالاَ حَدَّثَنَا وَكِيعٌ، عَنْ سُفْيَانَ، عَنْ مُحَمَّدِ بْنِ عَبْدِ الرَّحْمَنِ، مَوْلَى آلِ طَلْحَةَ عَنْ سَالِمٍ، عَنِ ابْنِ عُمَرَ، أَنَّهُ طَلَّقَ امْرَأَتَهُ وَهِيَ حَائِضٌ فَذَكَرَ ذَلِكَ عُمَرُ لِلنَّبِيِّ ﷺ فَقَالَ " مُرْهُ فَلْيُرَاجِعْهَا ثُمَّ لِيُطَلِّقْهَا وَهِيَ طَاهِرٌ أَوْ حَامِلٌ " .