For he knoweth our frame - Our formation; of what we are made; how we are made. That is, he knows that we are made of dust; that we are frail; that we are subject to decay; that we soon sink under a heavy load. This is given as a reason why he pities us - that we are so frail and feeble, and that we are so easily broken down by a pressure of trial.
He remembereth that we are dust - Made of the earth. Genesis 2:7; Genesis 3:19. In his dealings with us he does not forget of what frail materials he made us, and how little our frames can bear. He tempers his dealings to the weakness and frailty of our nature, and his compassion interposes when the weight of sorrows would crush us. Remembering, too, our weakness, he interposes by his power to sustain us, and to enable us to bear what our frame could not otherwise endure. Compare the notes at Isaiah 57:16.