14:17 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, Nu 14:18, and prayed for by Moses Nu 14:19, and granted by God in answer to him, 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.
14:11-19 Moses made humble intercession for Israel. Herein he was a type of Christ, who prayed for those that despitefully used him. The pardon of a nation's sin, is the turning away the nation's punishment; and for that Moses is here so earnest. Moses argued that, consistently with God's character, in his abundant mercies, he could forgive them.