Abu Dawood: Hadith 376

I used to serve the Prophet (ﷺ). Whenever he intended to wash himself, he would say: Turn your back towards me, So I would turn my back and hide him. (Once) Hasan or Husayn (may Allah be pleased with them) was brought to him and he passed water on his chest. I came to wash it. He said: It is only the urine of a female which should be washed; the urine of a male should be sprinkled over.

'Abbas (a narrator) said: Yahya b. al-Walid narrated the tradition to us. Abu Dawud said: He (Yahya) is Abu al-Za'ra'. Harun b. Tamim said on the authority of al-Hasan: All sorts of urine are equal.