Numbers 14:16,17

Not able His power was quite spent in bringing them out of Egypt, and could not finish the work he had begun and had sworn to do. Let the power of my Lord be great That is, appear to be great; discover its greatness; namely, the power of his grace and mercy, or the greatness of his mercy, in pardoning this and their other sins: for to this the following words manifestly restrain it, where the pardon of their sins is the only instance of this power, both described in God's titles, Numbers 14:18; and prayed for by Moses, Numbers 14:19; and granted by God in answer to him, Numbers 14:20.

Nor is it strange that the pardon of sin, especially such great sins, is spoken of as an act of power in God, because undoubtedly it is an act of omnipotent and infinite goodness.