Tafsir of Al-Kahf 18:66

Following the teacher is incumbent on the student

In verse 66: هَلْ أَتَّبِعُكَ عَلَىٰ أَن تُعَلِّمَنِ مِمَّا عُلِّمْتَ رُ‌شْدًا ، Sayyidna Musa (علیہ السلام) despite being a prophet and messenger of great resolve, has most reveren¬tially requested al-Khadir (علیہ السلام) if he could follow him to learn his knowl¬edge from him. This tells us that the etiquette of acquiring knowledge is nothing but that the student should show respect for the teacher and fol¬low him (as an individual who is eager to learn) - even if the student happens to be superior to his teacher. (Qurtubi, Mazhari)