An old Sufi tradition advises to speak only after our words have managed to pass through four gates.
At the first gate, we ask ourselves, "Are these words true?" If so, we let them pass on; if not, back they go.
At the second gate we ask; "Are they necessary?"
At the third gate we ask; "Are they beneficial?"
At the fourth gate, we ask, "Are they kind?"
If the answer to any of these is no, then what you are about to say should be left unsaid.