Musar על ראש השנה 33:14

This is obvious, for the Holy One, blessed be He, repays measure for measure (Sanhedrin 90a). Thus he who has mercy and does kindness with others, will also be shown mercy when he is judged and pardoned of his sins with kindliness. For such pardoning is justice, since it corresponds measure for measure to his practice. This is what our sages, of blessed memory, taught: "who is forgiven iniquity? he who overlooks transgression [committed against himself]" (Rosh Hashana 17a).

BEARING INSULTS: The second division of humility is in bearing insults. Behold, our sages, of blessed memory, explicitly said: "Who is forgiven iniquity? He who overlooks transgression" (Rosh Hashana 17b).