And it came to pass, when Rehoboam had established the kingdom,.... Or when the kingdom of Rehoboam was established; the tribes of Judah and Benjamin being firmly attached to him, and great numbers from the other tribes coming over to him, and things going on peaceably and prosperously during the three years that he and his people abode by the pure worship of God: and had strengthened himself; built fortified cities for the defence of himself and kingdom, Ch2 11:5, he forsook the law of the Lord; after he had reigned three years, and was become strong, and thought himself safe and secure on the throne, trusting to his strength: and all Israel with him; the greater part of them following the example of their king; of this defection, and the sins they fell into, see Kg1 14:22.