The Cattle - 6:54
"When those who believe in Our Verses come to you, they say, "Peace be upon you. Your Lord has made it a principle to be merciful. Therefore, whoever repents after an unintentional evil deed and corrects himself, know that He is Forgiving, Merciful."
Related:
The Cattle/6:12
"Say: "Whose are the heavens and the earth?"Say: "Allah´s". He has made it necessary to be merciful to Him. He will gather you on the Day of Resurrection about which there is no doubt. It is the unbelievers who have lost their character."