The Messenger of Allah ﷺ said, "The urine of a baby boy is sprinkled with water, while the urine of a baby girl is washed."Qatada said, "This applies as long as they have not yet started eating solid food. Once they begin eating, the urine of both is washed."
حدثنا عبد الصمد بن عبد الوارث حدثنا هشام عن قتادة عن أبي حرب بن أبي الأسود عن أبيه
قال رسول الله ﷺ بول الغلام ينضح عليه وبول الجارية يغسل قال قتادة هذا ما لم يطعما فإذا طعما غسل بولهما
Its isnad is sahih. Abu Harb bin Abu Aswad Duali was a trustworthy Basran, and the hadith was also narrated by Tirmidhi, who said it is hasan sahih. See our discussion of it in our commentary on Tirmidhi, 2/509-510. It will also come at 757 and 1148, and with this same isnad at 1149.