Num 14:19 Please pardon the iniquity of this people, according to the greatness of your steadfast love, just as you have forgiven this people, from Egypt until now.”
Numbers 14 mirrors the situation in Exodus 32. When spies are sent into the Promise Land, they return with bad news. Israel grows weak in faith and declares that they should return to Egypt. God wonders how long they will continue to rebel (v 11). Moses then prays that God forgive the people.
God accepts this prayer and replies that “I have pardoned, according to your word.” Moses’ prayer changes the heart of God. God had declared against Israel, but then pardoned. This pardoning was not because of anything the people did, but because of one righteous prayer.