en_tn/deu/31/06.md

Be strong and of good courage

"Be strong and courageous"

fear not, and do not be afraid of them

"do not fear them at all"

Yahweh your God ... with you ... fail you nor forsake you

Moses speaks to the Israelites as if they were one man, so the words "you" and "your" here are singular. (See: rc://en/ta/man/jit/figs-you)

he will not fail you nor forsake you

This can be treated as litotes and translated positively. Alternate translation: "he will always fulfill his promise to you and will always be with you" (See: rc://en/ta/man/jit/figs-litotes)