Al-Waqi'ah 56:79

<h2>Allah swears to the Greatness of the Qur'an</h2><p>The usage of La (in Fala) is not an extra character without meaning, as some of the scholars of Tafsir say. Rather it is used at the beginning of an oath when the oath is a negation. This is like when `A'ishah, may Allah be pleased with her said, "La by Allah! Allah's Messenger ﷺ did not touch any woman's hand at all. So in this way, the meaning is, "No! I swear by the Mawaqi` of the stars. The matter is not as you people claim - about the Qur'an - that it is a result of magic or sorcery, rather it is an Honorable Qur'an." Ibn Jarir said, "Some of the scholars of the Arabic language said that the meaning of:</p><p>فَلاَ أُقْسِمُ</p><p>(Fala! I swear) is, `The matter is not as you people have claimed.' Then He renews the oath again by saying, `I swear."'</p><p>فَلاَ أُقْسِمُ بِمَوَقِعِ النُّجُومِ</p><p>(Fala! I swear by the Mawaqi` of the stars.) Mujahid said, "The setting positions of the stars in the sky," and he said that it refers to the rising and setting positions. This was said by Al-Hasan, Qatadah and preferred by Ibn Jarir. Qatadah also …

Which none toucheth save the purified,

Which none shall touch but those who are clean:

Which (that Book with Allah) none can touch but the purified (i.e. the angels).

None can grasp it except the purified.