Is it obligatory to explain the reason for lowering the gaze from young men, and what is the ruling on smiling, shaking hands, and embracing them, knowing that lowering the gaze aims to avoid lust despite the ability to control it?

It is forbidden to look at a handsome beardless youth with lust, or with fear of arousal. He is to be treated like a woman in this regard if it is with lust. It is also forbidden to shake his hand or embrace him, because that is more intense than looking, and this is not permissible just because it is a social custom. As for smiling, it may be forbidden if looking is forbidden, because it can be a means to temptation. If a person is secure from finding pleasure in them and becoming attached to them, and there is a benefit in sitting with them, then he may do so; otherwise, he should keep away from them.