Momentarily and temporarily man may see some benefit, but in reality, the heart of man is darkened if he adopts a way of falsehood, and termites, as it were, begin to eat away at him from within. To cover one lie, a person must then conjure many more lies because the initial lie must be made to appear as if it were the truth. It is in this way that one’s moral and spiritual faculties begin to wither away from within, until finally one becomes so bold and impudent that he begins to forge lies against God Almighty as well, and will reject the Messengers of God and those divinely commissioned by Him, after which he is deemed ‘the most unjust’ or azlam, just as God Almighty states:
فَمَنۡ اَظۡلَمُ مِمَّنِ افۡتَرٰي عَلَي اللّٰهِ كَذِبًا اَوۡ كَذَّبَ بِاٰيٰتِهٖ
Meaning, who can be more unjust than the person who forges a lie and untruth against Allah the Exalted, or rejects His signs? Remember that falsehood is a most evil affliction and that it destroys a person. What could be a more grave consequence of falsehood than the fact that a person rejects the Messengers of God Almighty and becomes worthy of punishment from God by the rejection of His Signs? Therefore, adopt the truth.
(Malfuzat [English], Vol. 2, pp. 83-84)