Sahih al-Bukhari 153
Sahih al-Bukhari · Book 4: Ablutions (Wudu') · It is forbidden to clean the private parts with the right hand
Narrated Abu Qatada:
حَدَّثَنَا مُعَاذُ بْنُ فَضَالَةَ ، قَالَ حَدَّثَنَا هِشَامٌ ـ هُوَ الدَّسْتَوَائِيُّ ـ عَنْ يَحْيَى بْنِ أَبِي كَثِيرٍ ، عَنْ عَبْدِ اللَّهِ بْنِ أَبِي قَتَادَةَ ، عَنْ أَبِيهِ ، قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم " إِذَا شَرِبَ أَحَدُكُمْ فَلاَ يَتَنَفَّسْ فِي الإِنَاءِ، وَإِذَا أَتَى الْخَلاَءَ فَلاَ يَمَسَّ ذَكَرَهُ بِيَمِينِهِ، وَلاَ يَتَمَسَّحْ بِيَمِينِهِ " .
Allah's Messenger (ﷺ) said, "Whenever anyone of you drinks water, he should not breathe in the drinking utensil, and whenever anyone of you goes to a lavatory, he should neither touch his penis nor clean his private parts with his right hand."