Sahih Bukhari Volume 008, Book 075, Hadith Number 330.
Narated By 'Ali : Fatima complained about the blisters on her hand because of using a mill-stone. She went to ask the Prophet for servant, but she did not find him (at home) and had to inform 'Aisha of her need. When he came, 'Aisha informed him about it. Ali added: The Prophet came to us when we had gone to our beds. When I was going to get up, he said, "'Stay in your places," and sat between us, till I felt the coolness of the feet on my chest. The Prophet then said, "Shall I not tell you of a thing which is better for you than a servant? When you (both) go to your beds, say 'Allahu Akbar' thirty-four times, and 'Subhan Allah' thirty-three times, 'Alhamdu 'illah' thirty-three times, for that is better for you than a servant." Ibn Sirin said, "Subhan Allah' (is to be said for) thirty-four times."