It is not clear which stronghold is in view. It could be Adullam or another site somewhere in Moab or the En-gedi west of the Dead Sea.1 Adullam seems most likely since it is listed as a fortified city (Joshua 15:33–35; 2 Chronicles 11:7). However, the prophet Gad’s instructions to go into the land of Judah suggests another stronghold since Adullam was already in the land of Judah.2
4 And he left them with the king of Moab, and they stayed with him all the time that David was in the stronghold.