He that speaketh flattery to his friends - Noyes renders this, "He that delivers up his friend as a prey, the eyes of his children shall fail." So Wemyss, "He who delivers up his friends to plunder." Dr. Good, "He that rebuketh his friends with mildness, even the eyes of his children shall be accomplished." The Septuagint, "He announces evil for his portion; his eyes fail over his sons." The Vulgate, "He promises spoil to his companions, and the eyes of his sons fail." The word rendered "flattery" (חלק chêleq) properly means "that which is smooth, smoothness" (from חלק châlaq to be smooth); and thence it denotes "a lot" or "portion," because "a smooth stone" was anciently used to cast lots in dividing spoils; Deuteronomy 18:8. Here it is synonymous with plunder or spoil; and the idea is, that he who betrayeth his friends to the spoil or to the spoiler, the eyes of his children shall fail. The meaning in this connection is, that the friends of Job had acted as one would who should announce the residence of his neighbors to robbers, that they might come and plunder them. Instead of defending him, they had acted the part of a traitor. Schultens says that this verse is "a Gordian knot;" and most commentators regard it as such; but the above seems to give a clear and consistent meaning. It is evidently a proverb, and is designed to bear on the professed friends of Job, and to show that they had acted a fraudulent part toward him. In Job 17:4, he had said that God had hid their heart from understanding, and that wisdom had failed them. He "here" says that in addition to a want of wisdom, they were like a man who should betray his neighbors to robbers.
Even the eyes of his children shall fail - He shall be punished. To do this is a crime, and great calamity shall come upon him, represented by the failure of the eyes of his children. Calamity is not unfrequently expressed by the loss of the eyes; see Proverbs 30:17.

He that speaketh flattery - There is a great variety of meaning given to the terms in this verse. The general sense is, The man who expects much from his friends will be disappointed: while depending on them his children's eyes may fail in looking for bread.

(f) He that speaketh flattery to [his] friends, even the eyes of his children shall fail.
(f) He who flatters a man, and only judges him happy in his prosperity, will not himself only but in his posterity be punished.

He that speaketh flattery to his friends,.... As Job's friends did to him when they promised great outward prosperity, and a restoration to his former state, and to a greater affluence upon his repentance and reformation; or when they spoke deceitfully for God, pretending great regard to the honour of his justice and holiness, and therefore insisted on it that he must be a wicked man and an hypocrite, that was afflicted by him, as Job was:
even the eyes of his children shall fail; so hateful are some sins to God, and particularly deceitful tongues, and flattering lips, that he will punish them in their posterity; the eyes of their children shall fail for want of sustenance, and while they are looking in vain for salvation and deliverance out of trouble, see Exodus 20:4.

The Hebrew for "flattery" is "smoothness"; then it came to mean a prey divided by lot, because a smooth stone was used in casting the lots (Deuteronomy 18:8), "a portion" (Genesis 14:24). Therefore translate, "He that delivers up his friend as a prey (which the conduct of my friends implies that they would do), even the eyes," &c. [NOYES] (Job 11:20). Job says this as to the sinner's children, retorting upon their reproach as to the cutting off of his (Job 5:4; Job 15:30). This accords with the Old Testament dispensation of legal retribution (Exodus 20:5).