Mishkat al-Masabih

‘Uqba b. ‘Amir reported God’s Messenger as saying, “Avoid going in where women are.” A man said, “Messenger of God, tell me about the relatives of a woman’s husband,” to which he replied, “The relatives of a woman’s husband are death.”* *The word "death” is used to indicate a strong prohibition, the idea being that they are a cause of temptation to a man’s wife. (Bukhari and Muslim.)