Sahih al-Bukhari — One-fifth of Booty to the Cause of Allah (Khumus) — Hadith No: 3113
Translation
Narrated `Ali:Fatima complained of what she suffered from the hand mill and from grinding, when she got the news that some slave girls of the booty had been brought to Allah's Messenger (ﷺ). She went to him to ask for a maid-servant, but she could not find him, and told `Aisha of her need. When the Prophet (ﷺ) came, Aisha informed him of that. The Prophet (ﷺ) came to our house when we had gone to our beds. (On seeing the Prophet) we were going to get up, but he said, 'Keep at your places,' I felt the coolness of the Prophet's feet on my chest. Then he said, "Shall I tell you a thing which is better than what you asked me for? When you go to your beds, say: 'Allahu Akbar (i.e. Allah is Greater)' for 34 times, and 'Al hamdu Li llah (i.e. all the praises are for Allah)' for 33 times, and Subhan Allah (i.e. Glorified be Allah) for 33 times. This is better for you than what you have requested