"Also (forbidden are) women already married, except those whom your right hands possess. Thus has Allah ordained for you. All others are lawful, provided you seek them from your property, desiring chastity, not fornication. So with those among them whom you have enjoyed, give them their required due, but if you agree mutually after the requirement (has been determined), there is no sin on you. Surely, Allah is Ever All-Knowing, All-Wise." - Quran 4:24 (read more)

"Abu Huraira reported Allah's Messenger (may peace be upon him) as saying: The last hour would not come unless the Muslims will fight against the Jews and the Muslims would kill them until the Jews would hide themselves behind a stone or a tree and a stone or a tree would say: Muslim, or the servant of Allah, there is a Jew behind me; come and kill him; but the tree Gharqad would not say, for it is the tree of the Jews." - Sahih Muslim 41:6985 (read more)

"...[If] your friend became an atheist and did not believe in Islam, and he died in that state, as appears to be the case, then it is not permissible for the one who knew his situation to offer the funeral prayer for him or to say du’aa’ for him, or to wash him or shroud him or bury him in the Muslim graveyard..." - Islam Q&A