Ahmad ibn Muhammad from Uthman ibn Isa from Sama'ah who said: I asked Imam عليه السلام about the saying of Allah سبحانه وتعالى, the Mighty and Majestic, "And do not raise your voice in your prayer nor lower it too much" (Surah Al-Isra, 17:110). Imam عليه السلام said: "Lowering the voice (mukhafatah) is to recite below the level of your own hearing, and raising the voice (jahr) is to raise your voice loudly and strongly."