2 Chronicles 13:3
"And Abijah set the battle in array with an army of valiant men of war, even four hundred thousand chosen men: Jeroboam also set the battle in array against him with eight hundred thousand chosen men, being mighty men of valour."
Cross References (ranked by relevance)
2 Chronicles 11:1
And when Rehoboam was come to Jerusalem, he gathered of the house of Judah and Benjamin an hundred and fourscore thousand chosen men, which were warriors, to fight against Israel, that he might bring the kingdom again to Rehoboam.
1 Chronicles 21:5
And Joab gave the sum of the number of the people unto David. And all they of Israel were a thousand thousand and an hundred thousand men that drew sword: and Judah was four hundred threescore and ten thousand men that drew sword.