כִּי־ט֣וֹב יְ֭הֹוָה לְעוֹלָ֣ם חַסְדּ֑וֹ וְעַד־דֹּ֥ר וָ֝דֹ֗ר אֱמוּנָתֽוֹ׃
For the LORD is good; His mercy endureth for ever; and His faithfulness unto all generations.
Rashi on Psalms
and until generation after generation His faith will endure. Every expression of truth (אמת) and faith (אמונה) means the realization of a promise, that He makes true and assures His promise.