Hadith 518090
Chapter 56: Speech - كتاب الكلام
وَحَدَّثَنِي مَالِكٌ، أَنَّهُ بَلَغَهُ أَنَّ عَبْدَ اللَّهِ بْنَ مَسْعُودٍ، كَانَ يَقُولُ عَلَيْكُمْ بِالصِّدْقِ فَإِنَّ الصِّدْقَ يَهْدِي إِلَى الْبِرِّ وَالْبِرَّ يَهْدِي إِلَى الْجَنَّةِ وَإِيَّاكُمْ وَالْكَذِبَ فَإِنَّ الْكَذِبَ يَهْدِي إِلَى الْفُجُورِ وَالْفُجُورَ يَهْدِي إِلَى النَّارِ أَلاَ تَرَى أَنَّهُ يُقَالُ صَدَقَ وَبَرَّ وَكَذَبَ وَفَجَرَ .
Malik related to me that he heard that Abdullah ibn Masud used to say, "You must tell the truth. Truthfulness leads to right action. Right action leads to the Garden. Beware of lying. Lying leads to corruption, and corruption leads to the Fire. Don't you see that it is said, 'He speaks the truth and acts rightly,' and, 'He lies and is corrupt.' "
Reference Muwatta Malik 518090
USC-MSA web (English) reference : Book 56, Hadith 16