Abdullah ibn Mas`ud quoted Prophet Muhammad (peace and blessings of Allah be upon him) as saying,
Maintain truthfulness, for truthfulness leads to righteousness, and righteousness leads to Heaven; A man continues to maintain truthfulness until he is recorded in Allah’s book as truthful. Refrain from lying, for lying leads to blatant evil, and evil leads to Hell; A man continues to lie until he is recorded in Allah’s book as a liar." (Al-Bukhari, Muslim, Abu Dawud, and At-Tirmidhi)