'Useless' in the Bible

Then all the corrupt and useless men among the men who went with David reacted and said, "Because they did not go with us, we will not give them [anything] from the plunder which we recovered, {except} each [man may take] his own wife and children. They must take them along and go!"

I hate those devoted to useless idols, but I trust Yahweh.

You have said, '[It is] useless to serve God! What [is the] gain if we keep his requirements, and if we walk as mourners {before} Yahweh of hosts?