Sahih Bukhari Volume 008, Book 075, Hadith Number 342.

Narated By Warrad : (The freed slave of Al-Mughira bin Shu'ba) Al-Mughira wrote to Muawiya bin Abu Sufyan that Allah's Apostle used to say at the end of every prayer after the Taslim, "La ilaha illa-l-lahu wahdahu la sharika lahu; lahu-l-mulk wa lahu-l-hamd, wahuwa 'ala kulli shai'n qadir. Allahumma la mani'a Lima a taita, wa la mu'ta Lima mana'ta, wa la yanfa'u dhal-jaddu minkal-jadd.