In verse 28a the word chesed is used, which Good News Translation usually translates “constant love” (so Revised Standard Version here has steadfast love); but in parallel with covenant in line b, the word here is probably to be understood as loyalty (so Anderson, commenting on the word in verse 24: “loyalty to the Covenant promises”). So one possibility is “my faithfulness” (also Traduction œcuménique de la Bible). But the usual meaning “love” may be the one intended here and is what most translations have (see the similar verse 33a). New Jerusalem Bible has “I shall maintain my faithful love for him always.”

In languages in which covenant is represented by a verb phrase (“the promise I have made” or “what I have promised to do”), the translation of this verse will produce two lines with almost identical meanings, and in some cases it may be preferred to reduce them to one line.

Verse 29 I will establish his line for ever, and his throne as the days of the heavens is a promise that the Davidic dynasty will always endure, that Israel will always have as king a descendant of David’s. The same thought is expressed in verses 4, 36-37. Biblia Dios Habla Hoy has here “His descendants will reign in his place forever, as long as the sky lasts.”

The days of the heavens is a phrase found nowhere else in the Old Testament; Anderson takes it to mean “time that is practically endless.” A literal translation, such as Revised Standard Version, is practically meaningless; New International Version has “as long as the heavens endure”; New Jerusalem Bible “as long as the heavens last.”

Quoted with permission from Bratcher, Robert G. and Reyburn, William D. A Handbook on the Book of Psalms. (UBS Helps for Translators). New York: UBS, 1991. For this and other handbooks for translators see here .