Anas (Radiyallaahu `anhu) reported Allah’s Apostle (Sallallaahu `alayhi wa sallam) about the major sins. He (the Holy Prophet) observed:
“Associating anyone with Allah, disobedience to parents, killing a person and false utterance.”

Anas b. Malik (Radiyallaahu `anhu) reported Allah’s Messenger (Sallallaahu `alayhi wa sallam) said:
“Neither nurse mutual hatred, nor jealousy, nor enmity, and become as fellow brothers and servants of Allah. It is not lawful for a Muslim that he should keep his relations estranged with his brother beyond three days.”

Abu Hurairah (Radiyallaahu `anhu) reported Allah’s Messenger (Sallallaahu `alayhi wa sallam) said:
“The servant speaks words that he does not understand its repercussions but he sinks down in Hell-Fire farther than the distance between the east and the west.”

Abu Hurairah (Radiyallaahu `anhu) reported Allah’s last Messenger (Sallallaahu `alayhi wa sallam) said:
“Do you know what is backbiting?”
They (the Companions) said:
“Allah and His Messenger know best.”
Thereupon he (the Prophet) said:
“Backbiting implies your talking about your brother in a manner which he does not like.”
It was said to him:
“What is your opinion about this that if I actually find (that failing) in my brother which I made a mention of?”
He said:
“If (that failing) is actually found (in him) what you assert, you in fact backbited him, …

Ali Bin Abu Talib (Radiyallaahu `anhu) narrated that according to Allah’s Messenger (Sallallaahu `alayhi wa sallam) said:
“… If anyone introduces an innovation in the religion, he will be responsible for it. (Good or bad). If anyone introduces an innovation or gives shelter to a man who introduces an innovation (in the religion) he is cursed by Allah, by His angels and by all the people.”

The Prophet (Sallallaahu `alayhi wa sallam) said:
“The most truthful of speech is the Book of Allah and the best of guidance is the guidance of Muhammad, and the most evil of things are those which are newly-invented.”

Anas ibn Malik (Radiyallaahu `anhu) narrated that the Messenger of Allah (Sallallaahu `alayhi wa sallam) said,
“The Paradise is surrounded by hardships and the Hell-Fire is surrounded by temptations.’”

Abu Sa’eed al-Khudri (Radiyallaahu `anhu) narrated that the last Prophet of God (Sallallaahu `alayhi wa sallam) said,
“You will certainly follow the ways of those who came before you, span by span, cubit by cubit, until even if they were to enter a lizard’s hole, you would follow them.”
We said,
“O Messenger of Allaah, (do you mean) the Jews and Christians?”
He said,
“Who else?!”

Narrated by ‘Aisha (the wife of the Prophet) (Radiyallaahu `anha), The Prophet (Sallallaahu `alayhi wa sallam) said,
“The people will be resurrected (and judged) according to their intentions.”

Narrated by ‘Ali (Radiyallahu `anhu), the Prophet (Sallallaahu `alayhi wa sallam) said,
“Do not tell a lie against me for whoever tells a lie against me (intentionally) then he will surely enter the Hell-fire”