The urine of a baby girl is washed off, and the urine of a baby boy is sprinkled with water, so long as he has not yet started eating solid food.
حدثنا مسدد حدثنا يحيى عن ابن أبي عروبة عن قتادة عن أبي حرب بن أبي الأسود عن أبيه
يغسل من بول الجارية وينضح من بول الغلام ما لم يطعم
[Sahih] Bayhaqi related it, 2/415, from the hadith of Abu Dawud through him. Tirmidhi related it, no. 610, and Ibn Majah, no. 525, from the hadith of Qatada through him. See the following hadith as well. This hadith has many corroborating narrations.