Prophet Muhammad (peace be upun him) elevated the importance of morality in human life. He (peace be upun him) called for good manners, honesty, loyalty and chastity, and strengthened social bonds such as being dutiful to parents and relatives while always putting into practice what he preached. He (peace be upun him) prohibited and warned against such negative behaviors as lying, envy, betrayal, fornication and disrespect of parents, and he (peace be upun him) treated problems stemming from these diseases.
Allah praised His Prophet (peace be upun him) in the Qur'an, saying:
"And indeed, you are of a great moral character." (68:4)
Even before his prophethood, he (peace be upun him) was known as "the Trustworthy" due to his truthfulness and honesty. And when he emigrated from Makkah, he (peace be upun him) did not forget to make Ali bin Abi Talib responsible for returning all the possessions entrusted to him by their owners; some of whom were among the disbelievers of Quraysh that had expelled him from his homeland.
Thus, Prophet Muhammad (peace be upun him) always called for excellent character and encouraged it by speaking of the promise of reward. In fact, some of the many Qur'anic verses promoting good morals were the cause of a number of Makkans' acceptance of Islam. In the Prophet’s (peace be upun him) biography, it is mentioned that he (peace be upun him) recited Allah's words to two messengers from one of the tribal leaders:
"Indeed, Allah orders justice and good conduct and giving to relatives and forbids immorality and bad conduct and oppression. He admonishes you that perhaps you will be reminded." (16:90)
They returned to their chief and said,
"He spoke to us some words," and when they repeated them to their leader, he said,
"I see that he enjoins noble manners and prohibits bad ones."
Among the moral principles mentioned in the Qur'an are the following words of Allah:
Is the reward for good [anything] but good ? (55:60)
And speak to people what is good. (2:83)
And do not forget graciousness between you. (2:237)
Show lenience, enjoin what is good, and turn away from the ignorant. And if an evil suggestion comes to you from Satan, then seek refuge in Allah. Indeed, He is Hearing and Knowing. (7:199-200)
The moral principles mentioned in the Prophet's (peace be upun him) statements offer solutions to many of the psychological and social problems faced by those who have distanced themselves from his guidance. These he conveyed to people as a mercy for them, as instruction and salvation from distress in this world and from punishment in the Hereafter. Among them are:
The strong one is not he who knocks the other down; the strong one is he who controls himself when angry.
Do not get angry. (He (peace be upun him) repeated this several times to one who sought his advice.)
He who is not thankful to people is not thankful to Allah.
Among the best of you are those best in manners.
None of you [truly] believes until he likes for his brother what he likes for himself.