Why the Shema Is Spoken Aloud but Prayer in a Whisper

"And you shall teach them diligently to your children" (Deuteronomy 6:7) — that the words of Torah should be sharpened in your mouth. And just as you say, "Like arrows in the hand of a mighty man, so are the children of youth" (Psalms 127:4): that if a person comes to ask something of you, immediately tell it to him. "And you shall speak of them" — of them, and not in prayer; for the reciting of the Shema needs to be said in a strong voice so that they hear, but prayer in a whisper, just as Hannah did. "When you sit in your house" — this excludes one who is occupied with a commandment. "And when you walk by the way" — this excludes one who is a messenger for a commandment. "By the way" — this excludes a bridegroom who is marrying a woman; on the first night he is exempt from prayer, since he is preoccupied with a commandment. And the act of lying together is called "way," as it is said, "the way of a man with a maiden" (Proverbs 30:19). "And when you lie down" — at the time of lying down. "And when you rise up" — at the time of rising.