﴿ وَيَقُولُ ٱلَّذِينَ كَفَرُوا۟ لَسْتَ مُرْسَلًۭا ۚ قُلْ كَفَىٰ بِٱللَّهِ شَهِيدًۢا بَيْنِى وَبَيْنَكُمْ وَمَنْ عِندَهُۥ عِلْمُ ٱلْكِتَٰبِ ﴾

“And [if] they who are bent on denying the truth say [unto thee, O Prophet], "Thou hast not been sent [by God]", say thou: "None can bear witness between me and you as God does; and [none can bear witness as does] he who truly understands this divine writ.”

And he who possesses knowledge of the Book.Sahl said:The Book is noble (ʿazīz), and knowledge of the Book is even nobler, as is acting by it [that knowledge]. Action is noble, but sincerity in action is nobler still. Sincerity (ikhlāṣ) is noble, but witnessing (mushāhada) in [the state of] sincerity is nobler. Being in conformity (muwāfaqa) is noble, but intimacy (uns) in conformity is even nobler. Intimacy is noble, but the proprieties(ādāb) which are appropriate to intimacy are nobler still. And God, Transcendent and Exalted is He, knows best.His words, Exalted is He: