Thy words have upholden him that was falling - That is, either falling into sin, or sinking under calamity and trial. The Hebrew will bear either interpretation, but the connection seems to require us to understand it of one who was sinking under the weight of affliction.
The feeble knees - Margin, “bowing.” The knees support the frame. If they fail, we are feeble and helpless. Hence, their being weak, is so often used in the Bible to denote imbecility. The sense is, that Job, in the days of his own prosperity, had exhorted others to submit to God; had counselled them in such a manner as actually to give them support, and that the same views should now have sustained him which he had so successfully employed in comforting others.