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 tosay, "You must tell the truth. Truthfulness leads to right action.Right action leads to the Garden. Beware of lying. Lying leads tocorruption, and corruption leads to the Fire. Don't you see that it issaid, 'He speaks the truth and acts rightly,' and, 'He lies and iscorrupt.' " Translation Not Available

Book reference: Muwatta Imam Malik Book 56 Hadith 1829
Web reference: Muwatta Imam Malik Book 56 Hadith 16