The Thirteen Attributes of Divine Mercy are the centerpiece of the Selichos we recite during Elul, the עשרת ימי תשובה, the ten days of repentance, and on Yom Kippur.
ה' ה' אֵל רַחוּם וְחַנּוּן אֶרֶךְ אַפַּיִם וְרַב־חֶסֶד וֶאֱמֶת נֹצֵר חֶסֶד לָאֲלָפִים נֹשֵׂא עָוֺן וָפֶשַׁע וְחַטָּאָה וְנַקֵּה
Hashem, Hashem, a God compassionate and gracious, slow to anger, abounding in kindness and faithfulness, extending kindness to the thousandth generation, forgiving iniquity, transgression, and sin