Sahih al-Bukhari, Volume 8, Book 82, Hadith 799 (USC-MSA) ⓘ
Narrated Sahl bin Sa`d: The Prophet said, "Whoever guarantees me (the chastity of) what is between his legs (i.e. his private parts), and what is between his jaws (i.e., his tongue), I guarantee him Paradise."
حَدَّثَنَا مُحَمَّدُ بْنُ أَبِي بَكْرٍ، حَدَّثَنَا عُمَرُ بْنُ عَلِيٍّ. وَحَدَّثَنِي خَلِيفَةُ، حَدَّثَنَا عُمَرُ بْنُ عَلِيٍّ، حَدَّثَنَا أَبُو حَازِمٍ، عَنْ سَهْلِ بْنِ سَعْدٍ السَّاعِدِيِّ، قَالَ النَّبِيُّ صلى الله عليه وسلم " مَنْ تَوَكَّلَ لِي مَا بَيْنَ رِجْلَيْهِ وَمَا بَيْنَ لَحْيَيْهِ، تَوَكَّلْتُ لَهُ بِالْجَنَّةِ " .
also referenced under: Book 86, Hadith 37 (In-Book) & Hadith 6807 (DarusSalam)