Shemaiah ministered at the beginning of the divided monarchy. After the northern tribes rejected Rehoboam and made Jeroboam their king, Rehoboam gathered an army from Judah and Benjamin to restore the united kingdom by force.
The word of God came to Shemaiah, who commanded Rehoboam and the people not to fight their Israelite relatives. He declared that the division of the kingdom had occurred according to God's purpose. Rehoboam and his army obeyed and returned home (1 Kings 12:22-24).
Several years later, after Rehoboam and Judah abandoned the law of the Lord, Shishak king of Egypt invaded the land and threatened Jerusalem. Shemaiah confronted Rehoboam and the leaders of Judah, declaring that because they had forsaken the Lord, the Lord had allowed them to fall into Shishak's hands.
The king and his officials humbled themselves and acknowledged the righteousness of God. In response, God announced through Shemaiah that Jerusalem would not be completely destroyed, although Judah would experience subjection to Egypt (2 Chronicles 12:5-8).