Musannaf Ibn Abi Shayba 33:207

Abu Mu'awiyah narrated to us, from Juaybir, from al-Dahhak, who said: Abu Bakr al-Siddiq saw a bird perched on a tree and said: "Glad tidings to you, O bird! By Allah, I wish I were like you; you perch on the tree, eat from the fruit, and then fly away, with no reckoning upon you and no punishment." "By Allah, I wish I were a tree by the side of the road, and a camel passed by me, took me, put me in its mouth, chewed me, swallowed me, and then excreted me as dung, and that I had not been a human being."