O you who believe, beware of God, with regard to all vices by avoiding them, specifically the vice of mendacity, which is the significance of His words: and be with those who are truthful. For mendacity is the worst and vilest of vices as it is incompatible with virtuous manliness, for it is said, 'There can be no manliness in an inveterate liar'. That is because the purpose of speech, by which man is distinguished from all animals, is to inform the other of what he does not know. So when [this] information does not correspond [to the reality], the benefit of speech will not have been actualised and there will result from that a belief that does not correspond [to the truth], which is one of the specific qualities of satanic nature. A liar is thus a satan. And since mendacity is the vilest of vices, so truthfulness is the most virtuous of excellent qualities and the root of every good deed and the substratum of every praiseworthy characteristic and the foundation of all good and felicity, through which is actualised every perfection and every state. Its origin is truthfulness with regard to God's covenant, exalted be He, which is [itself] the result of sincere fulfilment of the compact of primordial nature or [the compact] itself, as He says: men who are true to the covenant they made with God [Q. 33:23] in the binding of resolve and the promise of creatures, as He says with regard to Ishmael: Indeed he was true to his promise [Q. 19:54]. If such [truthfulness] is borne in mind in all abodes, including those of incoming thought, consideration, intention, speech, deeds, then dreams, inrushes, states, stations, divine bestowals, and witnessings will all be true, as though it [truthfulness] were the root of the tree of perfection and the seed of the fruit of states.