people say good manners lead to richness (not wealth), while bad manners lead to misery. In a hadith, the Prophet (scw) said: 'through good manners, one reaches the status of a person who not only fasts, but who also stands late in the night to pray'
He (scw) also said: 'Shall I not inform you of the most beloved to me and the one seated close to me on the day of resurrection: 'those of you who are best in manners'
And verily, you O Muhammad are on an exalted standard of character (Qur'an 68: 4)
And by the mercy of Allah, you dealt with them gently. And had you been severe and harsh-hearted, they would have broken away from about you (Qur'an 3: 159)
And speak good to people (Qur'an 2: 83)
Aa'ishah (ra) described the Prophet (scw) with the following words
"his character was the Qur'an"