Midrash su Salmi 78:33

[(Gen. 24:1:) NOW ABRAHAM WAS OLD.] Come and see: From Adam even to Abraham there are twenty generation, but there is no < mention of > old age written about < any of > them except about him.¹⁷BM 87a; Sanh. 107b; Gen. R. 59:6; 65:9; below, 6:7; PRE 52. They sired children and grandchildren, but one did not recognize which was the son and which was the father. Also the children were striking the fathers without knowing it, as stated (in Ps. 78:33): SO HE ENDED THEIR DAYS IN FUTILITY AND THEIR YEARS IN TERROR, because they were all alike until Abraham came along. Then the Holy One gave him this < gray > crown which is an ornament for when one becomes old. And when did it come over him? When he practiced righteousness, since it is stated (in Prov. 16:31): GRAY HAIR IS A CROWN OF GLORY. And how do you find it? (Ibid., cont.:) IT IS FOUND BY WAY OF RIGHTEOUSNESS. To whom does this < verse > refer? To Abraham, concerning whom it is written (in Gen. 18:19): FOR I HAVE CHOSEN HIM SO THAT HE MAY CHARGE < HIS CHILDREN AND HIS HOUSEHOLD AFTER HIM TO KEEP THE WAY OF THE LORD, TO PRACTICE RIGHTEOUSNESS AND JUSTICE >…. The Holy One said to him: By your life, you are worthy of an old age. It is therefore stated (in Gen. 24:1): NOW ABRAHAM WAS OLD. Now David also received this crown, as stated (in I Kings 1:1): NOW KING DAVID WAS OLD. Why? Because he had acted according to Abraham's standard, as stated (in II Sam. 8:15): AND DAVID PRACTICED JUSTICE AND RIGHTEOUSNESS TOWARD ALL HIS PEOPLE. It is therefore stated (in Prov. 16:31): GRAY HAIR IS A CROWN OF GLORY.