Musnad Abu Ya'la al-Mawsili 127:4

Abu Bakr ibn Abi Shaybah and Zuhayr ibn Harb narrated to us, they said: Muhammad ibn Fudayl informed us, from Yunus ibn ‘Amr, from Burayd ibn Abi Maryam, from Anas ibn Malik, that the Messenger of Allah (peace and blessings of Allah be upon him) said: "Whoever asks Allah for Paradise three times, Paradise says: 'O Allah, admit him into Paradise.' And whoever seeks refuge with Allah from the Fire three times, the Fire says: 'O Allah, protect him from me.'"