Psalms 118:3 Kabbalah

יֹֽאמְרוּ־נָ֥א בֵֽית־אַהֲרֹ֑ן כִּ֖י לְעוֹלָ֣ם חַסְדּֽוֹ׃

So let the house of Aaron now say, For His mercy endureth for ever.

Read kabbalistic (mystical) interpretation of Psalms 118:3: and classical mystical sources.