Because the Lord had promised to make Israel as numerous as the stars in the sky

1 Chronicles 27:16--34

The leaders of the tribes of Israel: 

David did not take the number of the men twenty years old or less, because the Lord had promised to make Israel as numerous as the stars in the sky. Joab son of Zeruiah began to count the men but did not finish. God’s wrath came on Israel on account of this numbering, and the number was not entered in the book of the annals of King David.

Azmaveth son of Adiel was in charge of the royal storehouses.

All these were the officials in charge of King David’s property.

Ahithophel was the king’s counselor.

Why?

The Lord gave David enough smart men to manage his storehouses. Joab was honest, served David, and was a good commander of the royal army.

David made a mistake when he counted the number of Israel.

How?

Grace of the Lord is abundant so we don't need to compare it with others.