The Messenger of Allah ﷺ said, "When any of you urinates, he should not hold his penis with his right hand."
أخبرنا يحيى بن درست قال أنبأنا أبو إسمعيل وهو القناد قال حدثني يحيى بن أبي كثير أن
أن رسول الله ﷺ قال إذا بال أحدكم فلا يأخذ ذكره بيمينه
Agreed upon. Bukhari transmitted it, Book of Wudu, Chapter on the Prohibition of Cleaning Oneself with the Right Hand, hadith (153), and Muslim, Book of Purification, Chapter on the Prohibition of Cleaning Oneself with the Right Hand, hadith (267), from the hadith of Yahya bin Abu Kathir, through this chain. It is also found in Al-Kubra, hadith (29), and will come again at number (47).