"The punishment of those who wage war against Allah and His Messenger, and strive with might and main for mischief through the land is: execution, or crucifixion, or the cutting off of hands and feet from opposite sides, or exile from the land: that is their disgrace in this world, and a heavy punishment is theirs in the Hereafter;" - Quran 5:33 (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)

"Allaah tells us that there is no (true) believer who takes a kaafir as a friend, for whoever takes a kaafir as friend is not a believer. Imitation on the outside implies that a person loves (the one whom he imitates), and so it is forbidden." - Shaykh Al-Islam ibn Taymiyyah