don't form close bonds with Allah's enemies
Allah says: Idols you worship besides Allah only create affection between you in this worldly life (Al-Ankabut: 25).
Also: Believers, do not take My enemies and your enemies as close friends to whom you convey messages out of affection (Al-Mumtahanah: 1)
And: You will not find people who believe in Allah and the Last Day showing affection to those who oppose Allah and His Messenger (Al-Mujadilah: 22).
(from Syajaratul Ma‘arif, Syaikh al-‘Izz bin Abdus Salam)