You can't improve on saying nothing.

... silence (can) be the most eloquent form of lying.

Silence is one great art of conversation.

Nothing is so good for an ignorant man as silence, and if he knew this, he would no longer be ignorant.

Silence is the element in which great things fashion themselves together, that at length they may emerge, full-formed and majestic, into the daylight of Life, which they are henceforth to rule.

The right word may be effective, but no word was ever as effective as a rightly timed pause.

Keep your mouth shut and you won't get any flies in it. I believe in the discipline of silence and could talk for hours about it.

Silence is as full of wisdom and wit as the unhewn marble of great sculpture.

Silence is one of the hardest arguments to refute.

Well-timed silence is the purest speech.