Will not suffer, Heb. not give him license or commission. The destroyer, i.e. the destroying angel, which whether it were a good or bad angel is not agreed, nor is it necessary to determine.
Related Commentaries of Exodus 12:23
Exodus 12:23
23 For the LORD will pass through to smite the Egyptians; and when he seeth the blood upon the lintel, and on the two side posts, the LORD will pass over the door, and will not suffer the destroyer to come in unto your houses to smite you.