Sayyiduna Abu Rafi' (may Allah be pleased with him) narrates: Some people came to the Prophet (peace and blessings be upon him) and said: O Messenger of Allah! Of this kind of creature - meaning dogs - which you have ordered to be killed, what is lawful for us? Thereupon Allah, the Mighty and Majestic, revealed this verse: "They ask you what has been made lawful for them" [Surah al-Ma'idah: 4].
Hadith Referenceالمعجم الكبير للطبراني / باب الألف / 967