Musnad Ahmad 5:432

'Abdullah narrated to us, Ahmad ibn Muhammad ibn Yahya ibn Sa'id al-Qattan narrated to me, Azhar ibn Sa'd narrated to us, from Ibn 'Awn, from Muhammad, from 'Ubaydah, from 'Ali, who said: Fatimah complained to me about the calluses on her hands from grinding [grain]. So we came to the Prophet, peace and blessings of Allah be upon him, and I said: "O Messenger of Allah, Fatimah complains to you about the calluses on her hands from grinding, and she asks you for a servant." He said: "Shall I not guide you both to that which is better for you than a servant? At the time of your sleep, perform thirty-three [recitations] of glorification (tasbih), thirty-three of praise (tahmid), and thirty-four of magnification (takbir)."