The Messenger of Allah صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ said:
“Adopt truth, for truth shows the path of righteousness, and righteousness shows the path to Paradise. A man speaks the truth regularly and adopts truthful ways till he is recorded as a truthful person before ALLAH (سُبْحَانَهُ وَتَعَالَى). And keep away from falsehood, for falsehood leads to wickedness, and wickedness throws in Hell. A person tells lies regularly and attaches himself to falsehood till he is recorded as a liar before ALLAH (سُبْحَانَهُ وَتَعَالَى).”
[Fathul Bari]
Each person ends up on one of two lists with ALLAH (سُبْحَانَهُ وَتَعَالَى): that of “Truthful People” or that of “Liars.”
When a person feels that lying is not an option for them, they automatically stay away from many bad things out of the realisation that if they are caught they will feel embarrassed in admitting to those deeds.
The person who realizes that on the Day of Judgement they will not have an option to lie, and that even the parts of their own bodies will speak out against them and admit to the things they were used for, will restrain himself from doing as he pleases. Such a person will adopt good conduct and eventually be admitted to Jannah because of it. Their ultimate success of admittance to Jannah will have come out of adopting truth as their policy.
On the other hand, he who feels no compunction in lying, behaves as he pleases, and will have to pay the heaviest penalty for it on the Day of Judgement.
