Hadith 2678
Sayyiduna Uqbah bin Amir (may Allah be pleased with him) said: The Messenger of Allah (peace and blessings be upon him) said: "Do not go to women (in seclusion)." The Companions said: "O Messenger of Allah! Except for the in-laws (i.e., exempt the in-law)." He said: "The in-law is death itself."
Yahya bin Bustam said: By 'in-law' is meant the husband's relatives such as brothers, i.e., the woman's brother-in-law, etc.