Messenger of Allah ﷺ 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 ﷺ replied: The in-laws of the wife are death itself. (Using translation from Bukhārī 5232)  

أَنَّ رَسُولَ اللهِ ﷺ قَالَ «إِيَّاكُمْ وَالدُّخُولَ عَلَى النِّسَاءِ» فَقَالَ رَجُلٌ مِنَ الْأَنْصَارِ أَرَأَيْتَ الْحَمْوَ؟ قَالَ «الْحَمْوُ الْمَوْتُ»