Souls of Believers..

Narrated Umm Bishr, daughter of al-Bara’ ibn Ma’rur AbdurRahman ibn Ka’b told on his father’s authority that when death came to Ka’b, Umm Bishr, daughter of al-Bara’ ibn Ma’rur, visited him and said, “AbuAbdurRahman, if you meet so and so, give him a greeting from me.” He replied, “Allah forgive you, Umm Bishr, I shall be too occupied to do that.” She said, “AbuAbdurRahman, have you not heard Allah’s Messenger (peace be upon him) say that the souls of believers are in green birds which are suspended on and feed on the trees of Paradise?” On his replying that he had, she said that that was what she meant.
Ibn Majah and Bayhaqi, in Kitab al-Ba’th wan-Nushur, transmitted it.
Al-Tirmidhi – Hadith 1631