2 Chronicles 11:4
Thus saith the Lord, Ye shall not go up, nor fight against your brethren: return every man to his house: for this thing is done of me. And they obeyed the words of the Lord, and returned from going against Jeroboam.
Cross-reference
In 2 Chronicles 10:15, the cause of the division is stated — God's orchestration, which this verse obeys by turning back.
In 2 Chronicles 10:16, Israel's rebellion against Rehoboam is described — the very event that makes this command to not fight necessary.
In 2 Chronicles 28:8, Israel fights Judah and takes captives, directly opposing the command here not to fight their brethren.
In 2 Chronicles 25:7-10, a prophet warns against fighting with Israel — similar to this verse's command to not fight brothers.
In 2 Chronicles 28:9-15, Israel fights Judah and is rebuked — opposite of this verse where God forbids the fight.
In 1 Kings 11:29-38, Ahijah prophesies the kingdom's division — the event this verse references as God's doing.
In 1 Kings 12:24, the same command is recorded — this is the parallel account of the same event.