The Prophet (ﷺ) said, "Whenever anyone of you makes water he should not hold his penis or clean his private parts with his right hand. (And while drinking) one should not breathe in the drinking utensil ."
Sahih al-Bukhari Book 4, Hadith 20
← Previous Hadith 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."

Sahih al-Bukhari Book 4, Hadith 19 Next Hadith → I followed the Prophet (ﷺ) while he was going out to answer the call of nature. He used not to look this way or that. So, when I approached near him he said to me, "Fetch for me some stones for ' cleaning the privates parts (or said something similar), and do not bring a bone or a piece of dung." So I brought the stones in the corner of my garment and placed them by his side and I then went away from him. When he finished (from answering the call of nature) he used, them .

Sahih al-Bukhari Book 4, Hadith 21