Was the son of Siyámak and grandson of Kayúmars, and succeeded his great ancestor, ruling with justice and liberality. He is accounted the first to whom the name of sovereign virtually applies.* He came to India where he displayed the lustre of virtue. The work called ‘Eternal Wisdom’ is said to be the fruit of his mature experience.

Ḥáfiẓ,* in his Istiṭálah (Perillustris) says that when Mámún conquered Khurásán, the various chiefs sent presents to his court. The governor of Kábul sent a sage named Dúbán* on an embassy to Mamún and mentioned in his letter of homage that he was despatching to his court an offering of great price, than which nothing more valuable was known. The Caliph on receiving this information appointed his minister Faḍhl (Ibn-i-Sahl)* to inquire what it referred to. The envoy replied that the allusion was to himself. They said to him, “How doth a distinction so great concern such as thee?” He answered, “In enlightened knowledge, judicious counsel, and right guidance,” and he spoke such parables of wisdom that all were amazed. It happened that at this time the Caliph designed to enter upon hostilities against his brother Muḥammad u'l Amín and all parties were endeavouring to dissuade him from it. He therefore consulted Dúbán, whose clear-sighted reasoning confirmed his resolution of march­ing into I'ráḳ and pressing on the war. The sage's advice was the means of resolving all political difficulties. Mámún treated him with great favour and commanded that a large sum of gold should be bestowed upon him. Dúbán excused himself saying, “It is not the practice of my sovereign to allow his envoy to receive anything, but there is a work called ‘Eternal Wisdom’* composed by the farsighted intellect of Hushang and is said to to be in Madáin.* On the conquest of that country, when the Caliph obtains the work let him graciously bestow it upon me.” His proposal was assented to. When Madáin was taken, he pointed out that in a certain quarter of the city, by a certain tree there was a large stone. This they were to lift and to dig down till they came to a subterranean chamber in which were a number of chests and a large quantity of valuables, none of which were to be touched as the time for removing them had not arrived. In a certain corner of the chamber a box of a certain shape would be found which they were to bring out, wherein would be discovered the work they sought. Sharp-eyed and experienced men were sent in search, and all happened exactly as he had described. Some portion of this work was translated into Arabic at the pressing insistance of Faḍhl, but as it was treasured by Dúbán, he did not suffer its translation to be com­pleted.