And thus do we find that before Jacob's passing from the world he called his sons and rebuked them individually and then called all of them as one and said to them: Can it be that there is some reservation in your hearts about Him who spoke and brought the world into being? They answered "Hear, O Israel" (Jacob) — Just as there is no reservation in your heart, so there is none in ours, but (Devarim 6:4) "The L-rd our G-d, the L-rd is One!" — at which he said "Blessed is the Name of the glory of His Kingdom for ever and ever!"
And this is the intent of (Bereshith 47:31) "And Israel bowed at the head of the bed." Is this to be taken literally? (Obviously not. The intent is:) He expressed thanks and praise (to the L-rd) that "base matter" had not issued from him (thus, "his bed"). Others say: Reuven repented.
The Holy One Blessed be He said to Jacob: This is what you desired all of your days — that your sons "awake and retire" with the recitation of the Shema. This is the intent of (Devarim 6:4) "Hear, O Israel" (Jacob). Variantly: "Hear, O Israel": From here it was ruled that if one recited the Shema but did not make it audible to his ear, he did not fulfill his obligation.