In ancient Greek funerary art, the handshake is a gesture of farewell between the departed and survivors, or of reunion with ancestors in the afterlife. The deceased is depicted sitting or standing, and clasping the hand of someone who is typically shown standing. The gesture (sometimes referred to as dexiosis) is found also in Etruscan and Roman funerary art. Source
Fragment of a marble Attic relief, probably a tombstone. The handshake in funerary reliefs denotes farewell, 4th century BC.