Is it permissible to see the deceased and greet him with a handshake?

There is no objection to looking at the deceased's face after their soul has departed, shaking their hand, or kissing them as a farewell. This is supported by the actions of Abu Bakr and Aisha, may Allah be pleased with them both. There is no prohibition from seeing the deceased in a dream and greeting them by hand; Ibn al-Qayyim mentioned seeing many deceased individuals in dreams. As for shaking hands with the deceased after burial, it is not legislated, because exhuming the grave is forbidden except for a religious necessity. Rather, visiting them to greet them and supplicate for them is legislated.