Oh Lord, may I be directed what to do and what to leave undone

Leave undone whatever you hesitate to do

If you have got a jacket with a belt, you do not want to leave the belt undone, because it flops around and is distracting.

Faced with what is right, to leave it undone shows a lack of courage.

The whole point of getting things done is knowing what to leave undone.

What's done can't be undone.