The challenge that made even 'language masters' fall

This is a famous saying, showing respect to teachers, do you remember exactly what this saying is?

This is a famous saying about the tradition of gratitude, respect for teachers and valuing the teachings of morality. Fill in the blanks to complete the sentence.

Complete this sentence.

Once you find the answer, leave your answer in the comments section below.

Giang Pham

Source: https://vtcnews.vn/thu-thach-khien-bac-thay-ngon-ngu-cung-phai-guc-nga-ar987172.html