Musannaf Ibn Abi Shayba 21:411

Abu Mu'awiyah narrated to us, from al-A'mash, from Abu Ishaq, from Abu 'Ubaydah, who said: Abdullah was asked, "What is the supplication that you supplicated with on the night that the Messenger of Allah, may Allah bless him and grant him peace, said to you, 'Ask, and you shall be given'?" He said: I said, "O Allah, I ask You for faith that does not turn back, and bliss that does not run out, and the companionship of Your Prophet, Muhammad, may Allah bless him and grant him peace, in the highest degree of Paradise, the Paradise of Eternity."