Ante-Nicene Fathers/Volume V/Hippolytus/The Refutation of All Heresies/Book IX/Part 18
Chapter XVII.—The Tenets of the Esseni Continued.
All then pay attention to the president; and whatever injunctions he will issue, they obey as law. For they are anxious that mercy and assistance be extended to those that are burdened with toil. And especially they abstain from wrath and anger, and all such passions, inasmuch as they consider these to be treacherous to man. And no one amongst them is in the habit of swearing; but whatever any one says, this is regarded more binding than an oath. If, however, one will swear, he is condemned as one unworthy of credence. They are likewise solicitous about the readings of the law and prophets; and moreover also, if there is any treatise of the faithful, about that likewise. And they evince the utmost curiosity concerning plants and stones, rather busying themselves as regards the operative powers of these, saying that these things were not created in vain.