en_tn/1ch/17/25.md

will build him a house

To have children and develop a large family is described as building a house. (See: rc://en/ta/man/translate/figs-idiom)

have found courage

AT: "become courageous enough"

blessed it, and it will be blessed forever

Means the same thing, repeated here for emphasis. (See: rc://en/ta/man/translate/figs-parallelism)