It was narrated that al-Ash'ath bin Qais said : I visited 'Umar and he reached out and hit his wife. He said : O: Ash'ath, learn from me three things that I learned from the Messenger of Allah (ﷺ) ﷺ: Do not ask a man why he hit his wife, do not sleep until you pray Witr - and I forgot the third thing
Source: sunnah.com
Other translations
Arabic
حَدَّثَنَا سُلَيْمَانُ بْنُ دَاوُدَ يَعْنِي أَبَا دَاوُدَ الطَّيَالِسِيَّ، قَالَ حَدَّثَنَا أَبُو عَوَانَةَ، عَنْ دَاوُدَ الْأَوْدِيِّ، عَنْ عَبْدِ الرَّحْمَنِ الْمُسْلِيِّ، عَنِ الْأَشْعَثِ بْنِ قَيْسٍ، قَالَ ضِفْتُ عُمَرَ فَتَنَاوَلَ امْرَأَتَهُ فَضَرَبَهَا وَقَالَ يَا أَشْعَثُ احْفَظْ عَنِّي ثَلَاثًا حَفِظْتُهُنَّ عَنْ رَسُولِ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ لَا تَسْأَلْ الرَّجُلَ فِيمَ ضَرَبَ امْرَأَتَهُ وَلَا تَنَمْ إِلَّا عَلَى وَتْرٍ وَنَسِيتُ الثَّالِثَةَ.
sunnah.com