When Moses betook himself to those who had been bitten, hearing that they were too ill to come to him, they, conscious of their guilt, said to him: "We have sinned, because we have spoken against the Lord and against thee; pray unto the Lord, that He take away the serpents from us." Such was the meekness of Moses, that he instantly forgave the people's transgression in regard to himself, and at once implored God's aid. God also, however, forgave their sin as soon as they had shown penitence, and thus set an example to man likewise to grant forgiveness when it is requested.
The Serpents in the Wilderness and Israel's Confession
Legends of the Jews 5:82