Sahih al-Bukhari 4382
Book 64: Military Expeditions led by the Prophet (pbuh) (Al-Maghaazi) · Narrated by Anas
Arabic
حَدَّثَنَا أَبُو الْوَلِيدِ، حَدَّثَنَا شُعْبَةُ، عَنْ خَالِدٍ، عَنْ أَبِي قِلاَبَةَ، عَنْ أَنَسٍ، عَنِ النَّبِيِّ صلى الله عليه وسلم قَالَ " لِكُلِّ أُمَّةٍ أَمِينٌ، وَأَمِينُ هَذِهِ الأُمَّةِ أَبُو عُبَيْدَةَ بْنُ الْجَرَّاحِ ".
English translation
Narrated Anas:The Prophet (ﷺ) said, "Every nation has an Amin (i.e. the most honest man), and the Amin of this nation is Abu 'Ubaida bin Al-Jarrah
Reference: Sahih al-Bukhari 4382, Book of Military Expeditions led by the Prophet (pbuh) (Al-Maghaazi). English translation by Dr. Muhammad Muhsin Khan.