'Slack' in the Bible

All of them were wanting to scare us, supposing, "Their hands will grow slack from the work, and it won't get done." So now, strengthen my hands!

The one who is slack in his work is a brother to one who destroys.

Though at this time your ropes are slack, the mast is not secured, and the sail is not unfurled, at that time you will divide up a great quantity of loot; even the lame will drag off plunder.