‘Abdullah reported that the Prophet, may Allah bless him and grant him peace, said, “You must be truthful. Truthfulness leads to dutifulness and dutifulness leads to the Garden. A man continues to tell the truth until he is written as a siddiq with Allah. Beware of lying. Lying leads to deviance and deviance leads to the Fire. A man continues to lie until he is written as a liar with Allah.”
حَدَّثَنَا مُسَدَّدٌ، قَالَ‏:‏ حَدَّثَنَا عَبْدُ اللهِ بْنُ دَاوُدَ، عَنِ الأَعْمَشِ، عَنْ أَبِي وَائِلٍ، عَنْ عَبْدِ اللهِ، عَنِ النَّبِيِّ صلى الله عليه وسلم قَالَ‏:‏ عَلَيْكُمْ بِالصِّدْقِ، فَإِنَّ الصِّدْقَ يَهْدِي إِلَى الْبِرِّ، وَإِنَّ الْبِرَّ يَهْدِي إِلَى الْجَنَّةِ، وَإِنَّ الرَّجُلَ يَصْدُقُ حَتَّى يُكْتَبَ عِنْدَ اللهِ صِدِّيقًا، وَإِيَّاكُمْ وَالْكَذِبَ، فَإِنَّ الْكَذِبَ يَهْدِي إِلَى الْفُجُورِ، وَالْفُجُورَ يَهْدِي إِلَى النَّارِ، وَإِنَّ الرَّجُلَ لَيَكْذِبُ حَتَّى يُكْتَبَ عِنْدَ اللهِ كَذَّابًا‏.‏
Reference : Al-Adab Al-Mufrad 386
In-book reference : Book 21, Hadith 2
English translation : Book 21, Hadith 386