to hold one's peace: to keep silent, or to stay still and do nothing
At its heart this verb means to hold back, and Hebrew uses it for two kinds of restraint that English keeps apart. One is holding back the tongue: to say nothing, to keep silent. The other is holding back the hand: to stay still and do nothing when action is called for.
The silence sense runs from ordinary hushing, as when leaders quiet a crowd, to a heavy, deliberate refusal to speak. It carries special weight when God is the one who stays silent. In Isaiah he says he has long kept silent and will now finally cry out, and elsewhere his people beg him not to keep silent while they suffer, treating that silence as a withholding of help rather than mere quiet.
The inaction sense shows people sitting idle when they should be moving: a tribe that has scouted good land and is told not to hold back from taking it, a king who does nothing to reclaim his own city, lepers who realize they cannot keep quiet about good news. The same verb even describes a storm at sea falling still at God's command.
Hebrew sharpens the word by setting it beside its near neighbors. Isaiah pairs it with a verb for staying at rest (שׁקט), and a psalmist sets it next to a verb for being deaf and unhearing (חרשׁ), so that for God to keep silent would mean turning a deaf ear.