How can one invite an elderly, ill-tempered relative to pray? Is silence regarding advising him considered a sin? What is the ruling on shaking hands with non-mahram men?

The method of inviting someone to prayer varies from person to person. Some are influenced by good counsel, mentioning verses and hadith, and stories of the reward for the one who prays and the punishment for the one who abandons prayer. Others are affected by receiving a gift or a worldly service, coupled with expressing a desire for them to pray and increasing generosity towards them if they do pray. There are also those who are influenced by strictness and boycotting. The caller must understand the psychology of the invitee to deal with them appropriately. Effort must be expended in advising a close relative to pray in a suitable manner; otherwise, it would be a sin, as the Prophet, peace and blessings be upon him, said: "Whoever among you sees an evil, let him change it with his hand; if he cannot, then with his tongue; if he cannot, then with his heart—and that is the weakest of faith." As for shaking hands with this person, being alone with him, or appearing before him without a lawful hijab, it is forbidden as long as he is a stranger to her.