Charles Ellicott Commentary 1 Chronicles 22:8

"But the word of Jehovah came to me, saying, Thou hast shed blood abundantly, and hast made great wars: thou shalt not build a house unto my name, because thou hast shed much blood upon the earth in my sight." — 1 Chronicles 22:8 (ASV)

But the word of the Lord came to me (upon me).—Literally, And a word of Jehovah became upon me. There is a partial correspondence between this “word of the Lord” and what Nathan is represented as delivering (1 Chronicles 17:4–14). There, however, David is promised success in war, without any hint that warfare, as such, would unfit him for the sacred task he longed to undertake. And in 1 Kings 5:3, Solomon implies that David’s wars left him no leisure for the work.

You have shed blood. —The emphatic word is “blood.” Literally, Blood in abundance have you shed, and great wars have you made.

Because you have shed much blood. —A better translation is: for torrents of blood (plural) have you shed earthward before me.

The author of this narrative may well have remembered Genesis 9:5-6 and the denunciations of the prophets against "men of blood." One might especially compare Amos 1:3, Amos 1:13, and Amos 2:1 with David’s treatment of the conquered Ammonites (1 Chronicles 20:3). See also Hosea’s denunciation of vengeance upon the house of Jehu for the bloodshed of Jezreel (Hosea 1:4; Hosea 7:7).

Or, the verse may express the interpretation which David’s own conscience put upon the oracle forbidding him to build the Temple.