By the Deeds of the Law No Flesh Will be Justified

"…[A]nd under the word law he includes also the Prophets, and so the whole of the Old
Testament — That every mouth may be stopped, etc.; that is, that every evasion may be cut
off, and every occasion for excuse. It is a metaphor taken from courts of law, where the
accused, if he has anything to plead as a lawful defense, demands leave to speak, that he
might clear himself from the things laid to his charge; but if he is convicted by his own
conscience, he is silent, and without saying a word waits for his condemnation, being even
already by his own silence condemned. Of the same meaning is this saying in Job 40:4, 'I will
lay my hand on my mouth.' He indeed says, that though he was not altogether without some
kind of excuse, he would yet cease to justify himself, and submit to the sentence of God. The
next clause contains the explanation; for his mouth is stopped, who is so fast held by the
sentence of condemnation, that he can by no means escape. According to another sense, to
be silent before the Lord is to tremble at his majesty, and to stand mute, being astonished at
his brightness." – John Calvin