Good Manners and Form (Al-Adab)
Ṣaḥīḥ al-Bukhārī 6094
إِنَّ الصِّدْقَ يَهْدِي إِلَى الْبِرِّ، وَإِنَّ الْبِرَّ يَهْدِي إِلَى الْجَنَّةِ، وَإِنَّ الرَّجُلَ لَيَصْدُقُ حَتَّى يَكُونَ صِدِّيقًا، وَإِنَّ الْكَذِبَ يَهْدِي إِلَى الْفُجُورِ، وَإِنَّ الْفُجُورَ يَهْدِي إِلَى النَّارِ، وَإِنَّ الرَّجُلَ لَيَكْذِبُ، حَتَّى يُكْتَبَ عِنْدَ اللَّهِ كَذَّابًا
inna aṣ-ṣidqa yahdī ilā al-birri, wa-inna al-birra yahdī ilā al-jannah, wa-inna ar-rajula layaṣduqu ḥattā yakūna ṣiddīqan, wa-inna al-kadhiba yahdī ilā al-fujūri, wa-inna al-fujūra yahdī ilā an-nāri, wa-inna ar-rajula layakdhibu, ḥattā yuktaba ʿinda-Llāh kadhāban
Transliteration generated from the Arabic vowel marks
The full narration
Narrated `Abdullah:The Prophet (ﷺ) said, "Truthfulness leads to righteousness, and righteousness leads to Paradise. And a man keeps on telling the truth until he becomes a truthful person. Falsehood leads to Al-Fajur (i.e. wickedness, evil-doing), and Al-Fajur (wickedness) leads to the (Hell) Fire, and a man may keep on telling lies till he is written before Allah, a liar
Source
Ṣaḥīḥ al-Bukhārī · 6094