John Calvin Commentary Lamentations 3:29

"Let him put his mouth in the dust, if so be there may be hope." — Lamentations 3:29 (ASV)

He continues the same subject, for he describes to us people so subdued to obedience that they are ready to bear whatever God may lay on them. He then says that the sitting and the silence of which he spoke prevailed so much that God's children, even in extreme hardships, continued to persevere in their obedience.

For it sometimes happens that those who have made some progress in the fear of God prove their obedience and patience in some minor trial; but when they are severely tried, then the impatience they had previously checked breaks forth. Therefore, the Prophet teaches us here that God's children do not sufficiently prove their patience when they bear a moderate correction with a calm mind, unless they proceed to a higher degree of perseverance, remaining quiet and resigned even when the situation appears hopeless.

By saying that the faithful put their mouth in the dust, he means that they lie down humbly before God and acknowledge themselves to be as good as dead. What this means is this: in times of extreme affliction, the wise person will put his mouth in the dust, seeing things in such confusion that all his thoughts vanish because of the atrocity of evils; and so he implies that the wise person would have nothing to say.

Therefore, to put the mouth in the dust is to become mute, as if he had said that the faithful shut their mouths. This means they do not grumble against God nor give themselves over to complaints; they do not protest that an injustice is done to them, nor claim what unbelievers usually do when God deals severely with them.

In short, to put the mouth in the dust means to make no complaints and so to restrain ourselves so that no loud outcries come from our mouths. Thus, another phrase is used to describe the silence mentioned before.

That the Prophet here speaks of extreme trials can be easily gathered from the next clause, If so be that there is hope; this is not because the faithful doubt whether God would give them hope, for they have no doubt that God, who shines even in darkness itself by His word, would at length, by the outcome, prove that He is not unfaithful.

But the particle אולי (auli), as is well known, expresses what is difficult; for when anything appears to be incredible, the Hebrews say, If it may be. But here, as I have said, it does not imply a doubt.

For if the mind of a godly person fluctuates or doubts, how could he put his mouth in the dust? Rather, the Prophet shows that those who are taught to obey God persevere even in extreme trials, so that while nothing but despair appears, they still lie down humbly before God and patiently wait until some hope shines forth.

And here, 'hope' is to be understood as the basis or reason for hope.