It is narrated from Sayyidah Umm Ayyash (may Allah be pleased with her), and she was the slave-girl of Sayyidah Ruqayyah (may Allah be pleased with her), the daughter of the Messenger of Allah (peace and blessings be upon him); she said: "I used to help the Prophet (peace and blessings be upon him) perform ablution while I stood and he (peace and blessings be upon him) sat."
Hadith Referenceالمعجم الكبير للطبراني / مسند النساء / 21696