*Minor differences ignored. Grouped by changes, with first version listed as example.
Behold, now I am old, I know not the day of my death. There is not the least doubt that Isaac implored daily blessings on his sons all his life: this, therefore, appears to have been an extraordinary kind of benediction. Moreover, the declaration that he knew not the day of his death, is as much as if he had said, that death was every moment pressing so closely upon him, a decrepit and failing man, that he dared not promise himself any longer life. Just as a woman with child when the time of parturition draws near, might say, that she had now no day certain. Every one, even in the full vigor of age, carries with him a thousand deaths. Death claims as its own the foetus in the mother's womb, and accompanies it through every stage of life. But as it urges the old more closely, so they ought to place it more constantly before their eyes, and should pass as pilgrims through the world, or as those who have already one foot in the grave. In short, Isaac, as one near death, wishes to leave the Church surviving him in the person of his son.
I know not the day of my death - From his present weakness he had reason to suppose that his death could not be at any great distance, and therefore would leave no act undone which he believed it his duty to perform. He who lives not in reference to eternity, lives not at all.
And he said, behold, now I am old,.... See Gill on Genesis 27:1,
I know not the day of my death; how soon it will be; everyone knows he must die, but the day and hour he knows not, neither young nor old; and though young men may promise themselves many days and years, an old man cannot, but must or should live in the constant expectation of death.
I am old, and know not the day of my death - How soon I may die.
*More commentary available at chapter level.