Is kissing a wife's hand as an expression of love and affection, and kissing a mother-in-law's hand as a sign of closeness and endearment, contrary to Islamic Sharia?

If the marriage contract is concluded, everything that is permissible for other spouses becomes permissible for the husband from his wife. So, it is permissible to kiss her hand unless custom prevents it, and it is better to observe custom. As for the wife's mother, she becomes permanently forbidden to the husband simply by virtue of the marriage contract with her daughter. It is permissible to kiss her hand to please the wife, as long as it is not with lust or fear of temptation.