This passage appears in the Torah (Exodus 34:6-7) at the time that G-d proclaimed His readiness to do away with the Jewish People after the sin of the Golden Calf. According to R’ Yochanan’s interpretation (Rosh HaShanah 17b), Moshe felt that the sin of the Jewish People was so grievous that there was no possibility of his intercession on their behalf.

Thereupon, Hashem appeared to him in the form of a chazzan, a prayer leader, wrapped in a tallit , a prayer shawl, and taught him the Thirteen Attributes. saying, "Whenever Israel sins, let them recite this in its proper order and I will forgive them."

Thus, this appeal to G-d’s mercy reassures us both that repentance is always possible, and that G-d always awaits our return to Him. The implication is also plain that if we emulate G-d’s merciful ways, He will treat us mercifully in return.