An impediment. God uncovers to Isaiah that he can be something constructive to the individuals or something negative contingent upon how they react. A stumbling block or hindrance was a stone set in a wrestling ring which soldiers could use to trip their rival. “And he shall be for a sanctuary; but for a stone of stumbling and for a rock of offense to both the houses of Israel, for a gin and for a snare to the inhabitants of Jerusalem.” Isaiah 8:14 KJV see also 1 Peter 2:8