Rabi'a ibn Ka'b related, "I used to spend the night at the doorof the Prophet, may Allah bless him and grant him peace, and I would givehim his wudu' water." He said, "After a long period of the night had passed,I heard him say, 'Allah hears whoever praises Him,' and I heard him sayafter a long period of the night had passed, 'Praise be to Allah, Lordof the Worlds.'"
English reference: Book 50, Hadith 1218
Arabic reference: Book 1, Hadith 1218