Judah Halevi,
Kitab al Khazari (Kuzari) — Part Three
“ They stand without fatigue when occasion demands, they bow down when he bids them to do so, and sit at the proper moment. The eyes look as a servant looks at his master, the hands drop their play and do not meet, the feet stand straight, and all limbs are as frightened and anxious to obey their master, paying no heed to pain or injury. The tongue agrees with the thought, and does not overstep its bounds, does not speak in prayer in a mere mechanical way as the starling and the parrot, but every word is uttered thoughtfully and attentively. ”
