Anas reported: Whenever a man was brought to Umar ibn al-Khattab, may Allah be pleased with him, who had divorced his wife three times in one sitting, he would flog his back.
Source: Sharḥ Maʻānī al-Āthār 4488
Grade: Sahih (authentic) according to Ibn Hajar
عَنْ أَنَسٍ قَالَ كَانَ عُمَرُ بْنُ الْخَطَّابِ رضي الله عنه إِذَا أُتِيَ بِرَجُلٍ طَلَّقَ امْرَأَتَهُ ثَلَاثًا أَوْجَعَ ظَهْرَهُ
4488 شرح معاني الآثار باب الرجل يطلق امرأته ثلاث معاً
9/275 المحدث ابن حجر العسقلاني خلاصة حكم المحدث إسناده صحيح في فتح الباري