On it being disliked to clean oneself in the lavatory with the right hand and to touch the genitals with the right hand for no reason

Riyad as-Salihin (The Meadows of the Righteous)

by Imam Nawawi

298. Chapter: On it being disliked to clean oneself in the lavatory with the right hand and to touch the genitals with the right hand for no reason

1648. Abu Qatada reported that the Prophet, may Allah bless him and grant him peace, said, "When one of you urinates, he should not hold his private part with his right hand nor should he cleanse with his right hand, and he should not breathe into a (drinking) vessel." [Agreed upon]