Qur'aanic Verse 39:23:
23. Allahu nazzala ahsana alhadeethi kitaban mutashabihan mathaniya taqshaAAirru minhu juloodu allatheena yakhshawna rabbahum thumma taleenu julooduhum waquloobuhum ila thikri Allahithalika huda Allahi yahdee bihi man yashao waman yudlili Allahu fama lahu min hadin
23. Allah has sent down the best hadeeth [Qur’aan]6, a Book with oft-repeated passages resembling one another. Thereat shiver the skins of those that fear their Lord! And then their skins and their minds become receptive to Allah´s remembrance. That is Allah´s Guidance! He guides therewith whosoever He wills. And one whom Allah lets go astray has none to guide him.
6. Qur’aan describes itself as the best hadeeth. It does not mention, sanctify or authorize any other hadeeth book as a parallel – or even supportive – source for the Allah-approved Deen [way of life] of Islam for mankind.
The above is an extract from yet-to-be-published Qur'aanic Studies Manzil VI.