דאמר רשב"ל (בראשית מט, א) ויקרא יעקב אל בניו ויאמר האספו ואגידה לכם ביקש יעקב לגלות לבניו קץ הימין ונסתלקה ממנו שכינה אמר שמא חס ושלום יש במטתי פסול כאברהם שיצא ממנו ישמעאל ואבי יצחק שיצא ממנו עשו אמרו לו בניו שמע ישראל ה' אלהינו ה' אחד אמרו כשם שאין בלבך אלא אחד כך אין בלבנו אלא אחד באותה שעה פתח יעקב אבינו ואמר ברוך שם כבוד מלכותו לעולם ועד
As Rabbi Shimon ben Lakish said that it is written: “And Jacob called his sons and said, Gather around and I will tell you what will occur to you in the end of days” (Genesis 49:1). Jacob wanted to reveal to his sons when the complete redemption would arrive at the end of days (see Daniel 12:13), but the Divine Presence abandoned him, rendering him unable to prophesy. He said: Perhaps the Divine Presence has abandoned me because, Heaven forfend, one of my descendants is unfit, as was the case with my grandfather Abraham, from whom Ishmael emerged, and like my father Isaac, from whom Esau emerged. His sons said to him: Hear Israel, our father, the Lord is our God, the Lord is One. They said: Just as there is only one God in your heart, so too, there is only one in our hearts. At that moment Jacob our father said in praise: Blessed be the name of His glorious kingdom for ever and ever, as all his children were righteous.