Sayyiduna Anas bin Malik (may Allah be pleased with him) said that some people of the tribe of Qays came to the Prophet (peace and blessings be upon him) and asked him to send with them some people who would teach them the Qur'an. So he (peace and blessings be upon him) sent with them seventy men of the Ansar, among them Anas's maternal uncle, Haram bin Milhan. But they betrayed them and killed them. Haram was the first to be struck with a spear; the blood gushed from him, and he took it in his hand, raised it towards the sky and said: I have succeeded, by the Lord of the Ka'bah! Then Qur'an was revealed concerning them: "Convey from us (this message) that we have met our Lord, and He is pleased with us and has made us pleased."
Hadith Referenceالمعجم الكبير للطبراني / باب الحاء / 3594