Shloka 53
अवराणां समानानां शिष्याणां च समाचरेत् । पापमाचक्षते नित्यं हृदयं पापकर्मिण:
avarāṇāṁ samānānāṁ śiṣyāṇāṁ ca samācaret | pāpam ācakṣate nityaṁ hṛdayaṁ pāpakarmiṇaḥ ||
毗湿摩说：与地位较下者、同辈者，乃至弟子相处，可以用较为随和的称呼而无过。然作恶之人，其罪常由其心自显——纵欲以言辞遮掩，内里之性情终会出卖他。
भीष्म उवाच
Educational Q&A
Proper social conduct includes knowing when informal address is acceptable—toward juniors, equals, and students it is not inherently improper. More deeply, moral character cannot be fully masked: a sinful person’s inner heart/mind continually discloses his wrongdoing through attitude and behavior.
In the Anushasana Parva’s instruction section, Bhishma continues advising Yudhishthira on dharma and proper conduct. Here he links etiquette in forms of address with a broader ethical point: inner disposition (hṛdaya) is a reliable indicator of virtue or vice.