Truthfulness, trustworthiness, faithfulness, and honesty are Islamic traits that every Muslim should be distinguished with. Telling lies, dishonesty, and all evil and bad traits are not from Islam and Muslims, therefore, are not characterized by such traits.
The eminent Muslim scholar, Sheikh Yusuf Al-Qaradawi, states: “Telling lies is a bad conduct. It is not proper for righteous people and true believers; rather, it is a sign of hypocrisy, as the Prophet (peace and blessings be upon him) said: ‘The hypocrite has three characteristics: he tells lies, breaks his promise and breaches the trust.’ (Reported by Al-Bukhari and Muslim)
Also, Allah Almighty says, ‘Only they invent falsehood who believe not Allah’s revelations, and (only) they are the liars.’ (An-Nahl: 105)
Telling lies is not part of the human nature. It is completely rejected in Islam, and the Prophet (peace and blessings be upon him) warned Muslims against such evil trait, saying: ‘Stick to truthfulness, for it leads one to righteousness, and the latter leads to Paradise. Thus, when one sticks to truthfulness and shows keenness in it, Allah considers him as an absolutely truthful man. And avoid telling lies, for it leads to excessiveness, and this leads to Hell-Fire. Thus, when one persists in telling lies, Allah considers him as a liar.’
Therefore, truthfulness is a conduct that can be acquired by keenness and persistence in telling the truth – even if it requires a lot of effort. A Muslim should strive to accomplish such a noble characteristic so that he can set a good example to the coming generations.
There are levels of lying, i.e., the more harm lying causes, the more urgently it is rejected and the severer punishment for it will be. Thus, some lies are considered minor sins, while others are major ones.”