Messenger of Allah 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."  

قَالَ رَسُولُ اللَّهِ ﷺ إِذَا شَرِبَ أَحَدُكُمْ فَلاَ يَتَنَفَّسْ فِي الإِنَاءِ وَإِذَا أَتَى الْخَلاَءَ فَلاَ يَمَسَّ ذَكَرَهُ بِيَمِينِهِ وَلاَ يَتَمَسَّحْ بِيَمِينِهِ