The Ruling on Kissing and Shaking Hands With Female Relatives for Whom One is Not a Mahram
Question :
Every so often, I visit my family and my kin after having been away from them. Sometimes this is after a period of six months, and sometimes, a whole year and when I reach the house, the women greet me (young and old) with kisses which make me bashful and embarrassed and in truth, it is said that this is an extremely common custom in our society, and that it does not mean anything in our family, since it does not resemble, in their opinion, committing a sin. However, I who have acquired a good degree of Islamic education, all praise and thanks be to Allah remain embarrassed and confused regarding this matter. The question is: How can I avoid kissing the women, bearing in mind that, if I were to shake hands with them, they would be extremely angry with me and they would say: "He does not respect us," and: "He hates us," and: "He doesn't love us." (i.e., the love that exists between families, not the love between a man and a woman). Would I be considered to have committed a sin if I kissed them, bearing in mind that I do not have an evil intention in doing so?
Answer:
It is not permissible for a Muslim to kiss or shake hands with women other than his wife and those whom he cannot marry due to reasons of lineage. In fact, this is a forbidden act and a cause of trial and temptation (Fitnah) and the existence of evil deeds (such as adultery and fornication) and it has been confirmed from the Prophet SAW that he said:
"Verily, I do not shake hands with women."
And 'A'ishah, may Allah be pleased with her, said: "By Allah, the hand of the Messenger of Allah never touched the hand of a woman. He did not accept the pledge of allegiance from women except in words."
And a worse sin than shaking hands is kissing them, whether they are daughters of the paternal uncle, daughters of the maternal uncle or neighbors, or from any part of the tribe- all of this is forbidden according to the consensus of the Muslims , and it is one of the greatest causes of the occurrence of prohibited evil deeds (such as fornication and adultery).
Therefore, it is incumbent upon the Muslims to beware of this and to convince all of the women among the family and others who are accustomed to doing it, that it is forbidden, even though it may be the custom of the people. And it is not permissible for a Muslim man or woman to do it, even if it be the custom of their kin or their fellow citizens. Indeed, they must reject it and warn the community to content themselves with speech when offering salutations of peace without shaking hands and without kissing.
Source:
Ibn Baz
Fatawa Islamiyah, Vol. 5 Pages 115-116-117