Pahlavi Texts, Part III (SBE24), E.W. West, tr. [1885], at sacred-texts.com
1. The twenty-eighth subject is this, that, when they teach the Avesta, it is in like manner necessary
that they teach it properly and truly, and recite it with deliberation and composure (sâkinî). 2. And it is necessary for those who are taught to recite it connectedly, and to keep it ever in remembrance.
3. For it is declared in revelation, that the sacred being has decreed thus: 'As to every one who puts the Avesta away from his memory, I will put his soul as far from heaven as the width of the earth 1.' 4. And in the commentary of the Avesta it is related that, in former times, as to any one who had been taught the Avesta and had put it away from his memory, until the time he had again made it easy, they would have given him bread like that which they give to the dogs. 5. And in another place I have read that they would have given bread to him on the point of a spear.
291:1 Compare Chap. XCVIII, 3.