en_tn/psa/089/003.md

I have made a covenant with my chosen one

You can make explicit that "chosen one" refers to David. AT: "I made a promise to David, the one I chose" (See: rc://en/ta/man/translate/figs-explicit)

I have made

Yahweh is speaking in 89:3-4.

I will establish your descendants forever

Yahweh always causing one of David's descendants to be king is spoken of as if David's descendants are a building that Yahweh will build and make firm. (See: rc://en/ta/man/translate/figs-metaphor)

I will establish your throne through all generations

Here "throne" represents the power to rule as king. The psalmist speaks of God promising that one of David's descendants will always rule as king as if God will build David's throne and make it firm. AT: "I will make sure that one of your descendants will rule as king over every generation of my people" (See: rc://en/ta/man/translate/figs-metonymy and rc://en/ta/man/translate/figs-metaphor)

Selah

This may be a musical term that tells people how to sing or play their instruments here. Some translations write the Hebrew word, and some translations do not include it. See how you translated this in Psalms 3:2. (See: rc://en/ta/man/translate/translate-transliterate)