Protection against recorded call

Dear Sir/Madam, A friend of my cousin is facing a legal trouble. Friend's sister was sent divorce notice by the in-laws of the sister. In a fit of anger friend called the husband of the sister and hurled abuse to husband of sister. Plus perhaps/May be threatened husband of dire consequences. This whole thing was recorded by husband of sister on his smart phone and now husband of sister wants to peruse legal course against the friend. To the advantage of friend, he has not done any more interaction with husband, nor ever met husbsnd,nor seen husband after that.Overall friend has not done any harm to husband except a recorded verbal threat. Friend has checked for recording of phone call in his phone and could not find any recording of conversation.So friend does not have any recording with him. Question 1)How can friend obtain the recording of conversation Is there any software etching 2)How and what friend can say to court in case of FIR/Court case