What is the religious ruling on handshaking, and did the Rightly Guided Caliphs refrain from shaking hands? How do we respond to those who condemn not shaking hands, and what is the evidence for that?

The shaking of hands with women is divided into three categories:

1. The wife and mahram relatives: It is permissible to shake hands with them, unless there is a fear of fitna (temptation/strife) with a mahram relative.

2. The elderly woman: It is permissible to shake hands with her, as fitna is generally safe, though it is preferable to refrain from shaking her hand.

3. The young non-mahram woman: Shaking hands with her is forbidden by consensus, based on the saying of the Prophet, peace and blessings be upon him: "For one of you to be stabbed in the head with an iron needle is better for him than to touch a woman who is not lawful for him." This ruling is general for the Ummah and not specific to the Prophet, peace and blessings be upon him. The hadiths that indicate Umar or the Companions shaking hands with women are not authentic.