It is narrated from Sayyiduna Qurrah bin Iyas (may Allah be pleased with him) that a man said: O Messenger of Allah! If I lay a sheep down to slaughter it and I feel mercy for it (what is the ruling)? The Messenger of Allah (peace and blessings be upon him) said: "Even a sheep, if you show it mercy, Allah will show you mercy."
Hadith Referenceالمعجم الكبير للطبراني / باب القاف / 16094