Importance of the Sunnah.
Ḥasan al-Baṣrī رحمه الله reported that 'Imran bin ul-Hussain رضي الله عنه was sitting amongst his companions and a man arose and said: "Do not speak to us except with the Qur'ān." (i.e. leave the Sunnah)
So 'Imran bin ul-Hussain رضي الله عنه said to him: "Come here, do you see if you and your companions (those upon this same opinion as you) were left to the Qur'ān only, would you find if if that Ẓuhr is 4 Raka'aat and ‘Aṣr Prayer is 4 Raka'aat, and that Mahgrib is 3 wherein loud recitation occurs in the first 2?
Do you see if you and your companions are left to the Qur'ān only, would you find that Tawaaf is 7 circuits? And that Sa'ee is 7 times?
Then 'Imran bin ul-Hussain رضي الله عنه said: "O people! Take from us (i.e. Upon our way of taking Qur'ān & Sunnah), for indeed if you do not you will certainly go astray."
● [وأخرجه الخطيب في الكفاية صحفة ٤٨]