Allah swears the Messenger is True and His Words are a Revelation from Him
Ibn Abi Hatim recorded that Ash-Sha`bi and others stated that the Creator swears by whatever He wills among His creation, but the created only vow by the Creator.
Allah said,
وَالنَّجْمِ إِذَا هَوَى
By the star when it goes down.
Ibn Abi Najih reported that Mujahid said,
"The star refers to Pleiades when it sets at Fajr."
Ad-Dahhak said
"When the Shayatin are shot with it."
And this Ayah is like Allah's saying;
فَلَ أُقْسِمُ بِمَوَقِعِ النُّجُومِ
وَإِنَّهُ لَقَسَمٌ لَّوْ تَعْلَمُونَ عَظِيمٌ
إِنَّهُ لَقُرْءَانٌ كَرِيمٌ
فِى كِتَـبٍ مَّكْنُونٍ
لااَّ يَمَسُّهُ إِلااَّ الْمُطَهَّرُونَ
تَنزِيلٌ مِّن رَّبِّ الْعَـلَمِينَ
So, I swear by the setting of the stars. And verily, that is indeed a great oath, if you but know. That is indeed an honorable recitation. In a Book well-guarded. Which none can touch but the pure. A revelation from the Lord of all that exists. (56;75-80)
Allah said;
مَا ضَلَّ صَاحِبُكُمْ وَمَا غَوَى