Shaking Hands (And Other Physical Interactions) With Non-Mahâhirm (Mahrams)

Question:

Some men are in the habit of shaking hands with relatives whom they are not a Mahram to. But they do it by way of kinship or neighbourliness. What is the ruling on this? And is it enough for him if she places a piece of cloth over her hand, with the intention of screening her hand?

Answer:

It is not permissible for a man to shake hands with a woman who is unrelated to him, even if she placed a piece of cloth over her hand when shaking hands. And may peace and blessings be upon our Prophet, Muhammad and upon his family and Companions.

Permanent Committee for Research and Verdicts
Fatawa Islamiyah, Darussalam, volume 5, page 113