Good manners lead to prosperity, while bad ones lead to misery.
ln a hadith, the Prophet (Blessings and Peace be upon him) said:
"Through good manners, one reaches the status of the person who not only fasts, but who also stands late in the night to pray."

He (bpuh) also said:
"Shall I not inform you of the most beloved to me and the one seated closest 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 peoples. Qur'an 2: 83

'Aa'ishah (may Allah be pleased with her) described the Prophet (bpuh) with the following words: "His character was the Qur'an."

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