Purification (Kitab Al-Taharah)
Dawud :: Book 1 : Hadith 375
Narrated Lubabah daughter of al-Harith:
Al-Husayn ibn Ali was (sitting) in the lap of the Apostle of Allah (peace_be_upon_him). He passed water on him. I said: Put on (another) clothe, and give me your wrapper to wash. He said: The urine of a female child should be washed (thoroughly) and the urine of a male child should be sprinkled over.