A Midrash taught that God heals with the very thing with which God wounds. Thus, Israel sinned in Shittim (so called because of its many acacia trees), as says, And Israel abode in Shittim, and the people began to commit harlotry with the daughters of Moab (and also worshipped the Baal of Peor). But it was also through Shittim wood, or acacia-wood, that God healed the Israelites, for as reports, Bezalel made the Ark of acacia-wood.