What is the ruling of the Sharia concerning a Muslim's quarrel that causes harm to another Muslim, and is it permissible to refuse to reconcile with him?

Allah has forbidden harming Muslims and injustice in general, as stated in His Almighty saying: "The way is only against those who oppress people and transgress in the land without right. Those will have a painful punishment," and His Almighty saying: "And those who harm believing men and believing women for [something] other than what they have earned have certainly borne slander and manifest sin." And in the Hadith Qudsi: "O My servants, I have forbidden injustice for Myself and made it forbidden among you, so do not commit injustice against one another." And His صلى الله عليه وسلم saying: "Beware of injustice, for injustice will be darknesses on the Day of Resurrection."

And even though Allah has affirmed the right of the oppressed to seek justice for themselves, He has encouraged forgiveness, pardon, and reconciliation to repel evil with good, for in it there is the gathering of unity and the cutting off of the devil's influence. Allah has promised the oppressed good results from their forgiveness, including raising their status and honor, and the oppressor may even become a compassionate friend.

The proper way to deal with injustice is either forgiveness and pardon if it does not lead to corruption, or removing the injustice and repelling its evil without transgression, whether that is from the oppressed person themselves or from the ruler or the Muslim community.