Abdullah bin Abi Qatada Ibn Rab'i عبد الله بن أبي قتادة الأنصاري السلمي · The Book of Purification

"When any one of you urinates, let him not hold his penis in his right hand."

"The Messenger of Allah (ﷺ) said: 'When any one of you enters Al-Khala' (the toilet), let him not touch his penis with his right hand.'"

"When any one of you drinks, let him not breathe into the vessel, and when he goes to the toilet let him not touch his penis with his right hand, nor wipe himself with this right hand."