Why is my pain perpetual - i. e., Are all my labors to be in vain?

As a liar ... - Really, "as a deceitful brook," a brook which flows only in the winter, the opposite of the "perennial stream" of Amos 5:24. Jeremiah had expected that there would be a perpetual interference of Providence in his behalf, instead whereof things seemed to take only their natural course.

Wilt thou be altogether unto me as - waters that fail? - Leaning either springs, which in the height of summer grow dry; or, like that phenomenon in the sandy desert, where, by a peculiar action of the air on the rising vapors, the resemblance of water is produced, so that the traveler, deceived, rejoices that he is come, in the sandy desert, to the verge of a beautiful lake; but the farther he travels, it is still at the same distance, and at last vanishes; and he finds the whole was an illusion, for the waters have failed. Nothing can exceed the disappointment of the farmer whose subsistence absolutely depends on the periodical rains, when these fail, or fall short of their usual quantity. Some times the rice is sown and springs up in the most promising manner; but the latter rains fail, and whole fields of young rice wither and perish.

Why is my pain perpetual,.... The pain of his mind; his uneasiness for the good of his people, which was likely to last, having no hope of a change for the better: or it may design the pain which they gave him by their reproaches and persecutions of him, which seemed as if they would have no end:

and my wound incurable, which refuseth to be healed? the same thing is meant as before. The allusion is to an old ulcer, or obstinate wound, which no medicine can affect, is desperate and deadly; and such the prophet reckoned his case to be, or however deprecates it, and expostulates with God why it should be so:

wilt thou be altogether unto me as a liar, and as waters that fail? such God cannot be, nor did the prophet think he was; he knew that he was God that could not lie, and that he was faithful to his promises, and would not disappoint the faith, hope, and expectations of his people; but he feared he would be thought to be so by others, by his enemies, who would triumph over him, and say, where is thy God? did he not promise to make thee a defenced city, an iron pillar, and brasen walls? is he as good as his word? is he not like a dry brook, whose waters fail? are not thy hope and expectation in vain, who hast been trusting to him, and depending on him? and it is as if the prophet should say, Lord, let them have no occasion to speak after this manner; nor suffer my faith in thy promises to fail; show thyself to be as thou art, a covenant keeping God, and whose faithfulness never fails: to which an answer is returned in the following verses.

Why is my pain become perpetual? "My pain" is the pain or grief he feels at the judgment he has to announce to the people; not his pain at the hostility he has on that account to endure. נצח adverbial equals לנצח, as in Amos 1:11; Psalm 13:2, etc. "My wound," the blow that has fallen on him. אנוּשׁה, malignant, is explained by "(that) will not heal," cf. Jeremiah 30:12; Micah 1:9. The clause 'היו still depends on למּה, and the infin. gives emphasis: Wilt Thou really be? אכזב, lit., lying, deception, means here, and in Micah 1:16, a deceptive torrent that dries up in the season of drought, and so disappoints the hope of finding water, cf. Job 6:15. "A water," etc., is epexegesis: water that doth not endure. To this the Lord answers -

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.

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

fail: Heb. be not sure?

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.

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.