The trait of chessed-kindness is so great that our Sages said about it that even after the merit of the Forefathers is depleted, a person can still be spared from tribulations by clinging to the trait of doing chessed. About this it is written, My kindness shall not be removed from you (Yeshayah 54:10). The reason why this merit remains effective even after the merit of the Forefathers is depleted is that our Father Avraham in his good deeds would only do good and kindness with the whole world. Yitzchak and Ya’akov, as well, continued in his way, and with their good deeds they spread the glory of Hashem and His Divine Presence on the entire world. This became the root of zechus Avos — “the merit of the Forefathers” which protects their descendants. But since there is a limit to the extent of every merit, so even zechus Avos was depleted at some point. If a person wishes to draw upon himself the kindness of Hashem, he should use that very trait himself, and then Hashem will treat him in return “measure for measure” with the trait of Kindness and Mercy.