Good character is at the very heart of the Prophet's mission; he said, 'I was only sent to perfect noble character.' The Prophet ﷺ taught that the most complete believers in faith are those best in character, and that on the Day of Judgement nothing placed on the scale will be heavier than good character. He also linked it directly to Paradise, saying the thing that most admits people to Paradise is fear (taqwa) of Allah and good character. So for the Salaf, refining one's manners was not optional politeness but a core act of worship and a fruit of true iman.
Evidence — the daleel
On deen2u
Informational, not a personal fatwa. Consult a qualified scholar for rulings on your situation.