Musnad Ahmad 32:499

Yahya ibn Adam narrated to us, Yunus ibn Abi Ishaq narrated to us, from Burayd ibn Abi Maryam, from Anas, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "No Muslim man asks Allah for Paradise three times, except that Paradise says: 'O Allah, admit him.' And no Muslim man seeks refuge with Allah from the Fire three times, except that the Fire says: 'O Allah, grant him refuge.'"