God's promise is never fail.

2 Chronicles 9:13-30
Silver was considered of little value in Solomon's day.
King Solomon was greater in riches and wisdom than all the other kings of the earth.
Solomon reigned in Jerusalem over all Israel forty years.
The extent of Solomon's kingdom fulfills God's promise to Abraham.
V21 'Ships plying to Tarshih' in Spain is highly unlikely. Probably 'ocean-going ships' as in Kings.
V 29 All of these sources are now lost to us. Two of Ahijah's prophecies are recorded in 1 Kings 11 and 14.
David ruled over Israel forty years either.
How?
God's promise is never fail. His words are trust worthy!