The Quran itself directs us to the Messenger.
The Quran tells the believers, in more than one place, to obey and follow the Messenger. Read these verses slowly:
مَّآ أَفَآءَ ٱللَّهُ عَلَىٰ رَسُولِهِۦ مِنْ أَهْلِ ٱلْقُرَىٰ فَلِلَّهِ وَلِلرَّسُولِ وَلِذِى ٱلْقُرْبَىٰ وَٱلْيَتَٰمَىٰ وَٱلْمَسَٰكِينِ وَٱبْنِ ٱلسَّبِيلِ كَىْ لَا يَكُونَ دُولَةًۢ بَيْنَ ٱلْأَغْنِيَآءِ مِنكُمْ ۚ وَمَآ ءَاتَىٰكُمُ ٱلرَّسُولُ فَخُذُوهُ وَمَا نَهَىٰكُمْ عَنْهُ فَٱنتَهُوا۟ ۚ وَٱتَّقُوا۟ ٱللَّهَ ۖ إِنَّ ٱللَّهَ شَدِيدُ ٱلْعِقَابِ
That which Allah giveth as spoil unto His messenger from the people of the townships, it is for Allah and His messenger and for the near of kin and the orphans and the needy and the wayfarer, that it become not a commodity between the rich among you. And whatsoever the messenger giveth you, take it. And whatsoever he forbiddeth, abstain (from it). And keep your duty to Allah. Lo! Allah is stern in reprisal.
Al-Hashr 59:7 · Marmaduke Pickthall (en.pickthall)
مَّن يُطِعِ ٱلرَّسُولَ فَقَدْ أَطَاعَ ٱللَّهَ ۖ وَمَن تَوَلَّىٰ فَمَآ أَرْسَلْنَٰكَ عَلَيْهِمْ حَفِيظًۭا
Whoso obeyeth the messenger hath obeyed Allah, and whoso turneth away: We have not sent thee as a warder over them.
An-Nisa 4:80 · Marmaduke Pickthall (en.pickthall)
بِٱلْبَيِّنَٰتِ وَٱلزُّبُرِ ۗ وَأَنزَلْنَآ إِلَيْكَ ٱلذِّكْرَ لِتُبَيِّنَ لِلنَّاسِ مَا نُزِّلَ إِلَيْهِمْ وَلَعَلَّهُمْ يَتَفَكَّرُونَ
With clear proofs and writings; and We have revealed unto thee the Remembrance that thou mayst explain to mankind that which hath been revealed for them, and that haply they may reflect.
An-Nahl 16:44 · Marmaduke Pickthall (en.pickthall)
The Quran commands the prayer, but it is the Sunnah that shows how it is performed. The two are understood together, and that is why Muslims in every age have taken such care over hadith.