Pahlavi Texts, Part IV (SBE37), E.W. West, tr. [1892], at sacred-texts.com
Dk. VIII, Chap. XXII, 2, probably refers to the passage which contained the statement thus quoted in Sls. X, 13:—'It is revealed in the Ganabâ-sar-nigêd, where a day in the year is indicated, that the sacred thread-girdle of every one who shall be one day more than fourteen years and three months old 2 is to be tied on—it is better so than when he remains unto fifteen years, and then ties on the girdle—who is more cared for, that way, than those of five (or nine) months in the womb of the mother, on whom they should put it.'