Charles H. Spurgeon on Psalms 106:23

The breach. This is a metaphor taken from a city which is besieged, and in the walls of which the enemy having made a "breach" is just entering in, to destroy it, unless he be driven back by some valiant warrior. Thus Moses stood, as it were "in the breach", and averted the wrath of God, when he was just going to destroy the Israelites. See Ex 32:1-35. Thomas Fenton.