It is narrated from Sayyidah Umm Salamah (may Allah be pleased with her) that the Messenger of Allah (peace and blessings be upon him) said: "Water is to be sprinkled on the urine of a baby boy, and the urine of a baby girl is to be washed."
Hadith Referenceالمعجم الكبير للطبراني / مسند النساء / 20168