Sayyidah Umm Atiyyah (may Allah be pleased with her) said: We washed the daughter of the Prophet (peace and blessings be upon him). He (peace and blessings be upon him) ordered us to wash her with lote-tree leaves three times, or else five times, or else more than that. We considered that more than that would be seven times.
Hadith Referenceالمعجم الكبير للطبراني / مسند النساء / 21547