Sayyidah Umm Qays bint Mihsan (may Allah be pleased with her) said: I brought my suckling son to the Prophet (peace and blessings be upon him), and he urinated on him (peace and blessings be upon him). He (peace and blessings be upon him) called for water and sprinkled it over it.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 4150