Muwatta Malik #579

Yahya related to me from Malik from Ibn Shihab that Abd ar-Rahman ibn Kab ibn Malik al-Ansari told him that his father, Kab ibn Malik, used to relate that the Messenger of Allah, may Allah bless him and grant him peace, said, "The ruh of the mumin is a bird that sits in the trees of the Garden until Allah returns it to his body on the day He raises him ."