John Gill Commentary 2 Samuel 24:3

"And Joab said unto the king, Now Jehovah thy God add unto the people, how many soever they may be, a hundredfold; and may the eyes of my lord the king see it: but why doth my lord the king delight in this thing?" — 2 Samuel 24:3 (ASV)

And Joab said unto the king
Not so rudely and insolently as he did on account of his mourning for Absalom, but in a more modest, decent, and polite manner:

now the Lord your God add unto the people (however many they are) an
hundredfold ;
he wished his subjects were an hundred times more numerous than they were:

and that the eyes of my lord the king may see [it] ;
that he might live to see with his own eyes so great an increase:

but why does my lord the king delight in this thing ?
he being now old, and therefore it might seem strange to indulge such curiosity, pride, and vanity, and besides quite needless and useless: the numbering of them would not make them more or less; and they were all the king's servants, who were ready to obey him whenever he needed them, whether numbered or not; and it might be prejudicial to them, and bring down the wrath of God upon them, as well as be a troublesome and expensive business; all which, though not expressed here, is hinted at in (1 Chronicles 21:3) .