Story of the monk who is walking down the street with one of his students and this one bully comes by and attacks him.
The monk falls and keeps taking the beating.
Once the bully leaves, his student, all shaken up, asked why he did nothing to defend himself and teach the bully how wrong/bad is his behavior. The student also says, if you don’t stop him, he’ll hurt you again, he could have killed you.
The monk smiles, dusts himself off and simply replies “that is his problem, not mine”.