‘ And the king said to the guard who stood about him, “Turn, and slay the priests of YHWH, because their hand also is with David, and because they knew that he fled, and did not disclose it to me.” But the servants of the king would not put forth their hand to fall on the priests of YHWH.'
This fact is then accentuated by what follows. For when Saul calls on his guard to slay the priests of Nob because Ahimelech had clearly favoured David against the king, and had not disclosed to him that David had fled, they refused to respond. They were very unwilling to ‘fall on the priests of YHWH', especially on so flimsy a verdict. It is interesting that his own failure to react against them indicated that Saul too understood their qualms. It was because he was theoretically a Yahwist himself that he did so. He could therefore quite understand their reservations. But that being so it should have made him pull himself up and question what he was doing. Instead it simply made him look for someone less squeamish. he is revealed as clearly having no excuse for what he was doing.
So again the writer is bringing out the enormity of what Saul was doing. It could not fail to resound against him before the whole of Israel, and would for ever demonstrate to the discerning that he was rejected by YHWH. For he was not only behaving unjustly and contrary to the Law, but was also doing it towards those who were holy to YHWH. He was falsely judging and slaughtering people who were YHWH's own. It was sacrilege of the worst kind. It was the action of a man beyond the pale.
“The guard.” Literally ‘the runners', e.g. those who ran before him and attended him (compare 8:11, and see the use of the same word in 2 Kings 10:25).