And these words that I command you today shall be on your heart. You shall teach them diligently to your children, and shall talk of them when you sit in your house, and when you walk by the way, and when you lie down, and when you rise. —Deuteronomy 6:6–7
He leaves... no portion of time unoccupied with meditation on the Law; whether they are at home, or abroad, or when they retire to rest, or when they rise in the morning. ... [B]y the expression “talk of them,” Moses does not urge the people to empty talkativeness, to which many are too much inclined, but he would have them severally thus establish themselves and be teachers of each other. He enumerates these various engagements, lest that change of occupation by which the mind is wont to be distracted should withdraw the godly from the right path, as though he commanded them to make this their chief aim in whatever business they might be engaged. —Commentary on Deuteronomy
Not only in a book, not only in thought, but in the inmost feeling should they be the most precious treasure for you. For where your treasure is, there will your heart be also (Matt. 6:21). Therefore let nothing reign in your heart except faith and the love of God. ... For where they have first been in the heart in this way, there it will follow happily that they are also in your mouth. —Lectures on Deuteronomy, ed. Pelikan, 69.