en_tn/2ch/07/18.md

I will establish the throne of your kingdom

Here the throne represents ruling. Establishing the throne of Solomon's kingdom represents causing Solomon to have descendants who will rule over Israel. AT: "I will make descendants of yours rule over your kingdom" (See: rc://en/ta/man/translate/figs-metonymy)

A descendant of yours will never fail to be ruler in Israel

This can be stated positively. AT: "One of your descendants will always be ruler in Israel" or "Descendants of yours will always rule in Israel"