Musnad Ahmad 5:683

Aswad bin ‘Amir, Husayn, and Abu Ahmad al-Zubayri narrated to us, they said: Isra’il narrated to us, from Abu Ishaq, from Hubayrah bin Yarim, from ‘Ali, who said: I said to Fatimah: "If you were to go to the Prophet, may Allah bless him and grant him peace, and ask him for a servant, for the grinding and the work have exhausted you?" — Husayn said: "Indeed, the grinding and the work have exhausted you," and Abu Ahmad said the same — She said: "Then come with me." He said: So I went with her. We asked him, and the Prophet, may Allah bless him and grant him peace, said: "Shall I not guide you both to that which is better for you than that? When you go to your bed, then glorify Allah (say *SubhanAllah*) thirty-three times, and praise Him (say *Alhamdulillah*) thirty-three times, and magnify Him (say *Allahu Akbar*) thirty-four times. For that is one hundred on the tongue, and a thousand in the balance." ‘Ali, may Allah be pleased with him, said: "I have not left them since I heard them from the Prophet, may Allah bless him and grant him peace." A man said: "Not even on the night of Siffin?" He said: "Not even on the night of Siffin."