Muhammad bin Abi 'Adi محمد بن أبي عدي · The Book of ad-Dahaya (Sacrifices)

"There is no person who kills a small bird or anything larger, for no just reason, but Allah will ask him about it." It was said: "O Messenger of Allah, what does 'just reason mean?" He said: "That you slaughters it and eat it, and o not cut off its head and throw it aside,"