Musnad Ahmad 28:482

Rawh narrated to us, Shu'bah narrated to us, from 'Amr ibn Dinar, I heard Suhayb, the freed slave of 'Abdullah ibn 'Amir, from 'Abdullah ibn 'Amr, from the Prophet, peace and blessings of Allah be upon him, that he said: "Whoever kills a sparrow for no reason, except for its right, Allah the Almighty will ask him about it on the Day of Resurrection."