Deuteronomy 6:6-7

And these words which I am commanding you this day shall be [first] in your [own] minds and hearts; [then] You shall whet and sharpen them so as to make them penetrate, and teach and impress them diligently upon the [minds and] hearts of 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 up.