I've left so many things undone, and there's no more time, just none.
Rather than doing too much, it is best to leave things undone.
Regret for things done and undone could provoke change in the future.
You always leave with a lot of things undone.
There seem to be things yet undone before we meet once more and join our forces together.
Her maid was devoted to her and never left a thing undone.
There are many things yet undone, and we've no time to be haggling about.
Emil wouldn't leave a thing undone if he suspected that it could give him an advantage.
But, short on cash and long on deadline pressure, he left things undone.
Many times we have to leave things undone.