ENOfficial
Abu Sa'id reported God’s Messenger as saying, “When one of you beats his servant and he makes mention of God, you must stop beating him.” Tirmidhi and Baihaqi, in Shu'ab al-iman, transmitted it, but the latter has, “he should stop” instead of “you must stop beating him.”
Source: sunnah.com
Other translations
Arabic
وَعَنْ أَبِي سَعِيدٍ قَالَ: قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ: «إِذَا ضَرَبَ أَحَدُكُمْ خَادِمَهُ فَذَكَرَ اللَّهَ فَارْفَعُوا أَيْدِيَكُمْ» . رَوَاهُ التِّرْمِذِيُّ وَالْبَيْهَقِيُّ فِي شُعَبِ الْإِيمَانِ لَكِنْ عِنْدَهُ «فَلْيُمْسِكْ» بدل «فارفعوا أَيْدِيكُم»
sunnah.com