Sahih Muslim 267a
Sahih Muslim · Book 2: The Book of Purification · The prohibition of cleaning oneself with the right hand
Abu Qatada reported it from his father:
حَدَّثَنَا يَحْيَى بْنُ يَحْيَى ، أَخْبَرَنَا عَبْدُ الرَّحْمَنِ بْنُ مَهْدِيٍّ ، عَنْ هَمَّامٍ ، عَنْ يَحْيَى بْنِ أَبِي كَثِيرٍ ، عَنْ عَبْدِ اللَّهِ بْنِ أَبِي قَتَادَةَ ، عَنْ أَبِيهِ ، قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم " لاَ يُمْسِكَنَّ أَحَدُكُمْ ذَكَرَهُ بِيَمِينِهِ وَهُوَ يَبُولُ وَلاَ يَتَمَسَّحْ مِنَ الْخَلاَءِ بِيَمِينِهِ وَلاَ يَتَنَفَّسْ فِي الإِنَاءِ " .
The Messenger of Allah (ﷺ) said: None of you should hold penis with his right hand while urinating, or wipe himself with his right hand in privy and should not breathe into the vessel (from which he drinks).