(28) The days of Isaac were an hundred and fourscore years.--As Isaac was sixty when his sons were born, Jacob was one hundred and twenty years of age at his father's death, and one hundred and thirty when he appeared before Pharaoh (Genesis 47:9). Now, as Joseph was seventeen when sold into Egypt (Genesis 37:2), and thirty when raised to power (Genesis 41:46), and as the seven years of plenty and two of the years of famine had passed before Jacob went down into Egypt, it follows that the cruel deed, whereby he was robbed of his favourite child, was committed about twelve years before the death of Isaac.
Verse 28. - And the days of Isaac were an hundred and fourscore years. At this time Jacob was 120; but at 130 he stood before Pharaoh in Egypt, at which date Joseph had been 10 years governor. He was therefore 120 when Joseph was promoted at the age of 30, and 107 when Joseph was sold; consequently Isaac was 167 years of age when Joseph was sold, so that he must have survived that event and sympathized with Jacob his son for a period of 13 years.
35:21-29 What a sore affliction Reuben's sin was, is shown, and Israel heard it. No more is said, but that is enough. Reuben thought that his father would never hear of it; but those that promise themselves secrecy in sin, are generally disappointed. The age and death of Isaac are recorded, though he died not till after Joseph was sold into Egypt. Isaac lived about forty years after he had made his will, chap. 27:2. We shall not die an hour the sooner, but much the better, for timely setting our hearts and houses in order. Particular notice is taken of the agreement of Esau and Jacob at their father's funeral, to show how God had wonderfully changed Esau's mind. It is awful to behold relations, sometimes for a little of this world's goods, disputing over the graves of their friends, while they are near going to the grave themselves.
And the days of Isaac were an hundred and fourscore years. He lived, forty years after he had made his will, and blessed his two sons. Jacob was now one hundred and twenty years of age, being born when his father was sixty; and Joseph was now twenty nine years of age, so that Isaac lived twelve years after the selling of Joseph into Egypt; he was five years older than his father Abraham was when he died.