2 Samuel 24:8,9

When they had gone through all the land But not numbered all the people, for the work grew so tedious that they omitted Levi and Benjamin. Joab gave up the number of the people There are two returns left us of this numbering, (one here and the other 1 Chronicles 21,) which differ considerably from one another; especially in relation to the men of Israel; which, in the first, are returned but eight hundred thousand, but in the last, one million one hundred thousand. “But I think,” says Delaney, “a careful attendance to both the texts, and to the nature of the thing, will easily reconcile them. The matter appears to me thus: Joab, who resolved from the beginning, not to number the whole of the people, but who, at the same time, wished to show his own tribe in the best light, and make their number as considerable as he could, numbered every man among them, from twenty years old and upward, and so returned them to be five hundred thousand: but in Israel he only made a return of such men as were exercised and approved in arms: and therefore the number of persons above twenty years old is less in his return here than in Chronicles. In a word, here the whole of Judah is returned, and only the men of approved valour in Israel. In 1 Chronicles 21:5, the whole of Israel is expressly returned; but the particle all is not prefixed to those of Judah; and therefore possibly the men of tried valour in that tribe are only included in that return: and if so, the returns must of necessity be very different.” Perhaps, however, some mistake has been made in one of the texts by the copyists. In which case Houbigant prefers the smaller number.