en_tn/luk/01/72.md

to show mercy to

"to be merciful to" or "to act according to his mercy toward"

remember

Here the word "remember" means to keep a commitment or fulfill something.

his holy covenant, the oath that he spoke

These two phrases refer to the same thing. They are repeated to show the seriousness of God's promise to Abraham. (See: rc://en/ta/man/translate/figs-parallelism)