Prayer (Kitab Al-Salat): Detailed Injunctions about Witr
Dawud :: Book 8 : Hadith 1498
Narrated Abdullah Ibn Abbas:
The Apostle of Allah (peace_be_upon_him) went out from Juwayriyyah (wife of the Prophet). Earlier her name was Barrah, and he changed it. When he went out she was in her place of worship, and when he returned she was in her place of worship.
He asked: Have you been in your place of worship continuously? She said: Yes. He then said: Since leaving you I have said three times four phrases which, if weighed against all that you have said (during this period), would prove to be heavier: "glory be to Allah", and I begin with praise of Him to the number of His creatures, in accordance with His good pleasure, to the weight of His throne and to the ink (extent) of His words.