Can a man shake hands with a sister-in-law, if it is done without khalwat, in the presence of relatives and parents, which often occur in occasions such as holidays and so forth?
Answer: Should not a man shake hands with his brother's wife or his uncle's wife, as the prohibition shakes hands with other ajnabiyyah (non-mahram) ladies. Therefore, a man is not a mahram for his brother's wife, and so is uncle from father's side not mahram for his nephew's wife and maternal uncle is also not a mahram for his nephew's wife. And so are the uncle's children not mahram for the wives of their cousins. It is based on the words of the Prophet sallallaahu 'alaihi wasallam, "Actually, I did not shake hands with women." Aisha radhiyallahu' anha said, "By Allah, the hands of the Messenger of Allah sallallaahu 'alaihi wasallam never touch the hands of women. He does not question women, except by speech
