Jamieson, Fausset and Brown on Ecclesiastes 2:18-19

18-19. One hope alone was left to the disappointed worldling, the perpetuation of his name and riches, laboriously gathered, through his successor. For selfishness is mostly at the root of worldly parents' alleged providence for their children. But now the remembrance of how he himself, the piously reared child of David, had disregarded his father's dying charge (1Ch 28:9), suggested the sad misgivings as to what Rehoboam, his son by an idolatrous Ammonitess, Naamah, should prove to be; a foreboding too fully realized (1Ki 12:1-18; 14:21-31).