Sahih Bukhari Volume 9, Book 93, Hadith Number 526.

Narrated By Ibn Abbas : Allah’s Apostle used to say at the time of difficulty, “None has the right to be worshipped but Allah, the Majestic, the Most Forbearing. None has the right to be worshipped but Allah, the Lord of the Tremendous Throne. None has the right to be worshipped but Allah, the Lord of the Heavens and the Lord of the Honourable Throne. (See Hadith No. 357, Vol. 8)