And thou shalt know that the Lord thy God, he is a strong and faithful God, keeping his covenant and mercy to them that love him, and to them that keep his commandments, unto a thousand generations:
וְיָ֣דַעְתָּ֔ כִּֽי־יְהוָ֥ה אֱלֹהֶ֖יךָ ה֣וּא הֽ͏ָאֱלֹהִ֑ים הָאֵל֙ הַֽנֶּאֱמָ֔ן שֹׁמֵ֧ר הַבְּרִ֣ית וְהַחֶ֗סֶד לְאֹהֲבָ֛יו וּלְשֹׁמְרֵ֥י מצותו מִצְוֺתָ֖יו לְאֶ֥לֶף דּֽוֹר׃
One Church Father comments on this verse
God fulfills the promises made to the fathers by paving the way for their descendants, as noted in the scripture, "In the fourth generation they shall return this way" (Gen. 15:16). Furthermore, He showers His kindness upon a thousand generations for the benefit of righteous ancestors, as expressed in the words, "I will save Jerusalem for my sake, and David for the sake of my servant" (4 Sam. 19:34).
Passages read together with this verse.
THEOSIS