Abdullah bin Mas’ud (may Allah be pleased with him) narrated that the Prophet (peace be upon him) said:
“Truthfulness leads to Al Birr i.e. (piety, righteousness and every obedience to Allah) and Al Birr leads to Paradise , and a man keeps on telling the truth until he becomes a Siddiq i.e. (a truthful person).
Falsehood leads to Al Fujur i.e. (wickedness, evil-doing etc.) and Al Fujur leads to the Hell fire and the man keeps on telling lies till he is written as a liar before Allah.”
Also reported in – Sahih Muslim, Vol. 4, Ch. 1079, Hadith No. 6307