'Stronghold' in the Bible

So he left them in the care of the king of Moab, and they stayed with him the whole time David was in the stronghold.

Then the prophet Gad said to David, “Don’t stay in the stronghold. Leave and return to the land of Judah.” So David left and went to the forest of Hereth.

So David swore to Saul. Then Saul went back home, and David and his men went up to the stronghold.