Mishkat al-Masabih 13 Marriage كتاب النكاح 36

وَعَنِ ابْنِ عُمَرَ قَالَ: قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ: «إِيَّاكُمْ وَالتَّعَرِّيَ فَإِنَّ مَعَكُمْ مَنْ لَا يُفَارِقُكُمْ إِلَّا عِنْدَ الْغَائِطِ وَحِينَ يُفْضِي الرَّجُلُ إِلَى أَهْلِهِ فَاسْتَحْيُوهُمْ وَأَكْرِمُوهُمْ» . رَوَاهُ التِّرْمِذِيّ

Ibn ‘Umar reported God’s Messenger as saying, “Avoid being naked, for with you are those who never leave you (the recording angels) except when you are relieving yourselves and when a man has intercourse with his wife; so observe modesty before them and honour them.” Tirmidhi transmitted it.