Ali 'Imran · 3:118

118. O you who have faith in Allah and follow His Prophet, do not take unbelievers as close friends, letting them know your secrets and private business. They will not stop trying to harm you and ruin things for you, wanting what will hurt you and making things really difficult for you. Their hatred and hostility has appeared in what they say; in their criticism of your faith and worship, in incidents between you, and in them giving away your secrets. In their hearts they have even more hatred. Allah has made clear to you what is in your interests in this world and in the Afterlife, if you use your intellect to understand what your Lord has revealed to you.