It is narrated from Safwan bin Sulaim that a man said to the Messenger of Allah, peace be upon him: "May I lie to my wife?" The Messenger of Allah, peace be upon him, said: "Lying is not good and there is no goodness in it." Then the man said: "May I make a promise to my wife and say to her, 'I will do this for you, I will make this for you'?" The Messenger of Allah, peace be upon him, said: "There is no sin in that."

Imam Malik (may Allah have mercy on him) was informed that Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) used to say (Bukhari and Muslim have narrated this as a marfu' hadith): Consider truthfulness obligatory upon yourselves, for truthfulness leads to righteousness, and righteousness leads to Paradise. And beware of lying, for lying leads to wickedness, and wickedness leads to Hell. Have you not heard people say: So-and-so spoke the truth and became righteous, he lied and became wicked.

It reached Imam Malik, may Allah have mercy on him, that someone asked Hazrat Luqman, peace be upon him, "How did you attain such greatness?" Hazrat Luqman, peace be upon him, said: "By speaking the truth, by being trustworthy, and by avoiding useless deeds."

Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) used to say that when a person keeps lying, at first a black dot appears in his heart, then the whole heart becomes black, until (his name) is written among the liars with Allah.

It is narrated from Safwan bin Sulaim that someone asked the Messenger of Allah, peace and blessings be upon him: "Can a believer be a coward?" He, peace and blessings be upon him, replied: "Yes." Then he asked: "Can a believer be miserly?" He, peace and blessings be upon him, replied: "Yes." Then he asked: "Can a believer be a liar?" He, peace and blessings be upon him, replied: "No."