Volume 7, Book 62, Number 159:
Narrated ‘Uqba bin ‘Amir:
Allah’s Apostle said, “Beware of entering upon the ladies.” A man from the Ansar said, “Allah’s
Apostle! What about Al-Hamu the in-laws of the wife (the brothers of her husband or his nephews
etc.)?” The Prophet replied: The in-laws of the wife are death itself.