It was narrated from Abdullah bin Mas'ud that:
the Messenger of Allah (ﷺ) said: Verily there are two things - words and guidance. The best words are the words of Allah, and the best guidance in the guidance of Muhammad. Beware of newly-invented matters, for every newly-invented matter is an innovation (Bid'ah) and every innovation is a going-stray. Do not let the desire for a long life causes your hearts to grow hard. That which is bound to happen is close to you, and the only thing that is far away is that which is not going to happen. The one who is doomed to Hell is doomed from his mother's womb, and the one who is destined for Paradise is the one who learns from the lessons of others. Killing a believer constitutes disbelief (Kufr) and verbally abusing him is immorality (Fusuq). It is not permissible for a Muslim to forsake his brother for more than three days. Beware of lying, for lying is never good, whether it is done seriously or in jest. A man should not make a promise to a child that he will not keep. Lying leads to immorality and immorality leads to Hell. Truthfulness leads to righteousness and righteousness leads to Paradise. It will be said of the truthful person: 'He spoke the truth and was righteous', and it will be said of the liar, 'He told lies and was immoral.' For a person continues to tell lies until he is recorded with Allah as a liar.