Recording the conversation of a wife of whom one is suspicious

If a man hears from someone outside the home that his wife is talking to strange men on the phone in haraam ways, but he has no proof, is it permissible for him to install a device that will record all the conversations that go on in the house without his wife’s knowledge, so that he can find out whether this accusation is true or not?

Praise be to Allaah. 

We put this question to Shaykh ‘Abd-Allaah ibn Jibreen, may Allaah preserve him, who answered as follows:

If there is strong circumstantial evidence to that effect, and he knows that his wife is not very religious and not very trustworthy, then it is permissible for him to do that. And Allaah knows best.