Tafsir of Al-Anbiya' 21:50

وهذا ذكر مبارك أنزلناه

And this is a blessed Reminder which We have sent down; means, the Magnificent Qur'an, which falsehood cannot approach, from before it or behind it, revealed by the All-Wise, Worthy of all praise.

أفٲنتم له منكرون

will you then deny it! means, will you deny it when it is the utmost in clarity and truth!