Midrash su Salmi 33:9

It was taught that R. Ishmael, the son of R. Jose, said: "The older the disciples of the wise grow, the more wisdom they acquire; for it is written (Job 12, 11.) So is with the ancients, wisdom; and with length of days understanding. As to the ignorant, the older they grow, the more foolish they become; for it is said (Job 12, 20) He removeth the speech from trusty speakers, and taketh away the intelligence of the aged."

Also when men will be afraid of every elevation (Ecc. 12, 5), i.e., even a hillock appears to old men a mountain top; And are terrified on every way (Ib.). When they (the old) walk on the way, their hearts are full of fear; And the almond-tree will blossom (Ib.). This refers to the coccyx that gives way on account of age; And the locust will drag itself slowly along, refers to the rump of old men [which feels heavy]; And the desire will gainsay compliance, refers to the lust which disappears in the aged. R. Cahana was arranging collections of passages before Rab and when R. Cahana reached to the above passage, Rab gave a long-suffering sigh. R. Cahana remarked: "We understand from this that Rab had lost the feeling of youth" (and coming to this passage, he felt everything applicable to himself and therefore groaned). R. Cahana said: "What is meant by the passage (Ps. 33, 9.) For He spoke, and it came into being. This refers to a wife; He commanded, and it stood fast, refers to children." Also when men will be afraid of every elevation (Ecc. 12, 5), i.e., even a hillock looks to him (the aged man) like the highest mountain. And are terrified on every way (Ib.); when he walks on the road it (the road) becomes for him full of terrors. Because man goeth to his eternal home. (Ib.) R. Isaac said: "This teaches us that to every righteous person will be given a dwelling in accordance with his merits in the world to come; this may be likened to a mortal king who enters a city with his servants. When they enter, all are compelled to pass through the same gate, but when night comes, each one is given a berth in accordance with his rank." R. Isaac said further: "The worm is as painful to the dead body as a needle in sound flesh, as it is said (Job 14. 22.) But his body on him, feeleth pain." R. Chisda paid: "The soul of a man mourns for him the first seven days after his death, as it is said (Ib.) And his soul will mourn for him; and it is written (Gen. 50, 10.) And he made for his father a mourning of seven days."