The eminent Muslim scholar, Sheikh Yusuf Al-Qaradawi, states: Actually, some people claim that the Qur’an is so inclusive, that there is no need for the Sunnah (the Prophetic Tradition). They support their claim by citing the Qur’anic verse, (And We reveal the Scripture unto thee as an exposition of all thing…) (An-Nahl 16: 89)

However, this claim is completely wrong and rejected by the Qur’an itself. Allah Almighty says: (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)
In addition, Allah declares that obeying the Prophet is obligatory, as it is part of obedience to Him (See: 3: 31; 4: 80; 33: 36; 47: 33; etc.) Therefore, it is not proper for a Muslim who knows Islamic Law to make such a claim.
By and large, the Qur’an sets the general rules without details. For example, there is no mention in the Qur’an that there are five obligatory prayers to be performed daily. Nor is the number of rakh`ahs of each prayer specified, as well as the percentage to be paid in Zakah; the details in the rituals of Hajj, and other such ordinances and dealings. All of these details are profoundly dealt with in the Sunnah.