Good character is an attribute of the Master of the Messengers صلى الله عليه وسلّم, and the best of the works of the veracious (Siddiqeen). It is in reality half of religion, the fruits of the spiritual struggles of the god-fearing, and the efforts of the worshippers.
Lowly character is a killing poison, a deadly destroyer, a humiliating abaser, clear lowliness, and filth that distances one from the sanctuary of the Lord of the worlds.
Lowly character makes the one characterized by it of the Satans, and it is the open door to the burning fire of Allah, that Leaps up over the hearts (of men),(Quran, 104: 7) as good character is the open door to the bounties of the Gardens and proximity to the Merciful. Lowly character is a sickness of the heart and a disease of the lower self. It is a sickness that endangers the ever-lasting life.
Thus, it is necessary to pay utmost attention to it, even more than outward sickness.
Taken from advices of Shaykh Faraz Rabbani on Anger & Acquiring good Character