Shaykh Dr. Yasir Qadhi explicitly elaborates on the importance of having good manners in Islam. What constitutes good manners? Some of them are listed below.
Our Prophet ﷺ said, "Verily, I have only been sent to perfect good manners."
Whenever someone came to the Prophet ﷺ for advice, it always was more often than not related to perfection of good manners.
People can be never given a better blessing from Allah than good manners. It is the best treasure one can have.
The Prophet ﷺ said that a righteous Muslim can achieve the level of an elite Muslim who is firm in fasting and praying by simply having good manners.
Our Prophet ﷺ said that having good manners is a sign of Iman.
Allah loves good manners and He hates debased manners.
Good manners are the weightiest and heaviest things on the Meezan on the Day of Judgement apart from Iman and Taqwa.
Our Akhlaq will dictate our closeness with the Prophet ﷺ on the Day of Judgement as is mentioned in a Hadith.