Here "Sihon" and "Og" refer to two Kings of the Amorites and their armies. See how you translated these names in [Deuteronomy 1:4](../01/03.md). AT: "he did to Sihon and Og, the kings of the Amorites, and to their armies" (See: [[rc://en/ta/man/translate/figs-synecdoche]])
This can be treated as litotes and translated positively. AT: "he will always fulfill his promise to you and will always be with you" (See: [[rc://en/ta/man/translate/figs-litotes]])