Are there types of discord that vary depending on the individuals or situations involved, such as discord with relatives compared to fleeting squabbles, and does the sin cease if one party attempts to end the discord?

The Sharia prohibits quarreling and shunning without a legitimate religious reason. The prohibition of shunning becomes more emphasized as the right of the shunned person increases in importance. In the incident of the student, if you exceeded the limit in punishing him, you must repent and seek forgiveness from his guardian. It is not permissible for the guardian to shun you. You did well by initiating the greeting, for the best of those who shun each other is the one who initiates the greeting. As for the sin of punishment, it is expiated by repentance and seeking forgiveness. There is no sin upon you if the guardian continues to shun you after you initiated the greeting.