Could 'harm', when more broadly applied to other contexts, mean to not criticise the person whom God is using? After all, if God is using them, who can stand against them? Standing against them would be like standing against God.

Indeed, this was Miriam and Aaron's experience, who spoke against Moses for taking a Cushite (Ethiopian) wifeThey spoke against Moses presumably because he should have taken an Israelite wife, for other women served other gods, Deuteronomy 7:3-4. However, it's unclear whether they received that law by that time, given it is chronologically after Numbers 12, though the law itself may have been given earlier and only communicated at that time.. God himself summoned them, spoke to them face to face, and gave Miriam leprosy, sending Aaron begging to Moses to pray on her behalf (Numbers 12).

We learn from Numbers 12 that because God spoke to Moses face to face (12:8a), finding him a true and faithful servant (12:7), that others should have been afraid to speak against Moses (12:8b).

Yet, David criticises Saul not just once, but three times, in our series' passage (1 Samuel 24:1-22).

1. David criticises Saul by calling out his murderous intentions: "though you hunt my life to take it" (24:11).

2. He calls out Saul's error in believing a lie: "Why do you listen to the words of men who say, 'Behold, David seeks your harm'?" (24:9)

3. David uses wisdom of the day to call out his own goodness, and Saul's wickedness: "As the proverb of the ancients says, 'Out of the wicked comes wickedness.' But my hand shall not be against you." (24:13) This is contrast to Saul's hand that is against David, so that David's statement is at once also criticising Saul.

But this criticism was a righteous judgment, and Saul agreed (24:17-18), and repented (24:16b), leaving his pursuit of David's death (24:22).

Could it be then that what God said about being afraid of speaking against Moses, was not a blanket rule to not criticise, but rather to show respect, and not come with criticism lightly?

Indeed, Jethro, Moses' father-in-law, on seeing Moses take on all the people's disputes by himself, rebuked him and showed him a better way, by sharing the load (Exodus 18). This was a righteous judgment, and Moses took the advice, appointing many other judges (18:24-26). (More on this later.)

So while a rash criticism can easily produce gossip, slander, and breaking of trust, a wise and understanding criticism can produce much good fruit.