2 Samuel 24:8-10

8They went through all the land and after nine months and twenty days came back to Jerusalem.

9Joab reported the number of warriors to the king. In Israel there were 800,000 sword-wielding warriors, and in Judah there were 500,000 soldiers.

10David felt guilty after he had numbered the army. David said to the Lord, “I have sinned greatly by doing this! Now, O Lord, please remove the guilt of your servant, for I have acted very foolishly.”