Why is my pain perpetual, and my wound incurable, which refuseth to be healed? wilt thou be altogether to me {r} as a liar, and as waters that fail?

(r) And have not assisted me according to the promise? In which it appears that in the saints of God is imperfection of faith, which through impatience is often assailed as in Jer 20:7.

Wesley's Notes

15:18 Why - Jeremiah, though a great prophet, was (as Elijah) a man subject to like passions with other men.

King James Translators' Notes

fail: Heb. be not sure?

Jamieson-Fausset-Brown Bible Commentary

18. (Jer 30:15). "Pain," namely, the perpetual persecution to which he was exposed, and his being left by God without consolation and "alone." Contrast his feeling here with that in Jer 15:16, when he enjoyed the full presence of God, and was inspired by His words. Therefore he utters words of his natural "infirmity" (so David, Ps 77:10) here; as before he spoke under the higher spiritual nature given him.

as a liar, and as-rather, "as a deceiving (river) . waters that are not sure (lasting)"; opposed to "living (perennial) waters" (Job 6:15). Streams that the thirsty traveller had calculated on being full in winter, but which disappoint him in his sorest need, having run dry in the heat of summer. Jehovah had promised Jeremiah protection from his enemies (Jer 1:18, 19); his infirmity suggests that God had failed to do so.

Matthew Henry's Concise Commentary

15:15-21 It is matter of comfort that we have a God, to whose knowledge of all things we may appeal. Jeremiah pleads with God for mercy and relief against his enemies, persecutors, and slanderers. It will be a comfort to God's ministers, when men despise them, if they have the testimony of their own consciences. But he complains, that he found little pleasure in his work. Some good people lose much of the pleasantness of religion by the fretfulness and uneasiness of their natural temper, which they indulge. The Lord called the prophet to cease from his distrust, and to return to his work. If he attended thereto, he might be assured the Lord would deliver him from his enemies. Those who are with God, and faithful to him, he will deliver from trouble or carry through it. Many things appear frightful, which do not at all hurt a real believer in Christ.