Charles Ellicott Commentary 1 Kings 4:20

"Judah and Israel were many as the sand which is by the sea in multitude, eating and drinking and making merry." — 1 Kings 4:20 (ASV)

Were many. —The description of the people's condition here and in 1 Kings 4:25—as multiplied in numbers, and living in festivity and peace—is clearly intended to specify not only their general prosperity and wealth, but also the fact noted in 1 Kings 9:20–22: at this time they were a dominant people, relieved from all burden of labor, and ruling over the subject peoples, now reduced to complete subjection and servitude. (That the situation was different later is clear from the complaints to Rehoboam in 1 Kings 12:4.)

Now, for the first time, Israel entered into full possession of the territory promised during the Conquest (Joshua 1:4), and thus into the complete fulfillment of the promise to Abraham, alluded to in the words, many as the sand which is by the sea in multitude (Genesis 22:17).