The Book of Oaths
27/8. Chapter:
Treatment of slaves, and the expiation of one who slaps his slave
Sahih Muslim
وَحَدَّثَنِيهِ بِشْرُ بْنُ خَالِدٍ، أَخْبَرَنَا مُحَمَّدٌ، - يَعْنِي ابْنَ جَعْفَرٍ - عَنْ شُعْبَةَ، بِهَذَا الإِسْنَادِ وَلَمْ يَذْكُرْ قَوْلَهُ أَعُوذُ بِاللَّهِ أَعُوذُ بِرَسُولِ اللَّهِ صلى الله عليه وسلم .
This hadith has been narrated on the authority of Shu'ba with the same chain of transmitters, but made no mention of (these words) of his: I seek refuge with Allah, I seek refuge with Allah's Messenger (ﷺ).
Reference : Sahih Muslim 1659eIn-book reference : Book 27, Hadith 57USC-MSA web (English) reference : Book 15, Hadith 4089