This verse is very similar to 1 Chr 22.10, and the same ideas are expressed in 1 Chr 28.6-7, 10.

He shall build a house for me: This clause contrasts with verse 4, where David is told that he is not the person who would build the Temple. In Hebrew the pronoun for He is emphatic. Here it may be best to translate “He will be the one to build…” (Good News Translation, Contemporary English Version), “As for him, he will build…” (Knoppers), or “It is he who will build…” (Revised English Bible, Bible en français courant, Traduction œcuménique de la Bible). A house may be rendered “a temple” (Good News Translation, Biblia Dios Habla Hoy).

And I will establish his throne for ever: This clause adds to what has already been said in the previous verse about making the rule of this king secure. The added element here is the expression for ever, which ensures the continuity of the dynasty beyond the life of the individual ruler. Translators should ensure that the figurative use of throne is clearly understood as referring to the dynasty. For this whole clause NET Bible says “and I will make his dynasty permanent.”

Quoted with permission from Omanson, Roger L. and Ellington, John E. A Handbook on 1-2 Chronicles, Volume 1. (UBS Helps for Translators). Miami: UBS, 2014. For this and other handbooks for translators see here .