What is the ruling on speaking to an adulterer?

Speaking with an adulterer is obligatory if it is to enjoin him to cease the evil, and permissible if for another need, unless one intends to befriend him, in which case it is forbidden. This is because a Muslim must distance himself from evil companions, and foremost among them are adulterers, for "A person will be with whom he loves," and "Close friends, that Day, will be foes to one other, except for the righteous."