A story from Zen Flesh, Zen Bones (compiled by Paul Reps):
When Zen master, Gasan was studying under Tekisui, his teacher was very severe. Sometimes he even beat Gasan.
Other pupils would not stand this type of teaching and quit.
Gasan remained, saying:
A poor disciple utilises a teacher’s influence.
A fair disciple admires a teacher’s kindness.
A good disciple grows strong under a teacher’s discipline.