Musnad Ahmad 175:14

Sa'd ibn Ibrahim narrated to us, my father narrated to us, from Salih, from Ibn Shihab, who said: Abd al-Rahman ibn Abd Allah ibn Ka'b narrated to me that it reached him that Ka'b ibn Malik said: The Messenger of Allah, peace and blessings of Allah be upon him, said: "The soul of the believer, when he dies, is a bird that hangs from the trees of Paradise until Allah, Blessed and Exalted is He, returns it to his body on the day He resurrects him."