Jacob kicks Richard's ass, dunks him in the ocean

Richard makes his way to the beach and sees the what remains of the Taweret statue. There is just the foot left as we've seen in the present, and there are broken pieces in the water and on land right around  the foot. Richard takes out the dagger and approaches the statute. He sees the entrance open, but is suddenly punched by Jacob.

Jacob beats him down and takes the dagger. He asks Richard who gave him the dagger, and Richard asks where Isabella is. When Richard reveals that Isabella is dead, Jacob asks if he met a man dressed in black. Richard confirms that he did and says that he told him that Jacob was the devil and that he needed to kill him to see Isabella again. Jacob tells Richard that it wasn't really Isabella and that he is not dead and the island is not hell.

Jacob grabs Richard and forces him under the water numerous times, repeatedly asking if he still thinks he's dead. Richard finally says that Jacob should stop because he wants to live. Jacob then stops and says that they need to talk.

So Jacob's line of questioning here seems to insinuate that this may be the first time the man in black has tried to kill him. We also see Jacob hostile and angry for the first time. It's a long way from his mellow, somewhat zen persona we've seen in the later years of his life.