Albert Barnes Commentary 1 Kings 4:29

"And God gave Solomon wisdom and understanding exceeding much, and largeness of heart, even as the sand that is on the sea-shore." — 1 Kings 4:29 (ASV)

Largeness of heart - What we call “great capacity.” The expression that follows is common in reference to numerical multitude (1 Kings 4:20), but its use here to express simple amplitude or greatness is unique.