Language:
كتاب المغازى
64  
Military Expeditions led by the Prophet (pbuh) (Al-Maghaazi)
(35)
Chapter: The Ghazwa of Al-Hudaibiya
(35)
باب غَزْوَةِ الْحُدَيْبِيَةِ
Sahih al-Bukhari 4154

Narrated Jabir bin `Abdullah:

On the day of Al-Hudaibiya, Allah's Messenger (ﷺ) said to us' "You are the best people on the earth!" We were 1400 then. If I could see now, I would have shown you the place of the Tree (beneath which we gave the Pledge of Allegiance)." Salim said, "Our number was 1400."

حَدَّثَنَا عَلِيٌّ، حَدَّثَنَا سُفْيَانُ، قَالَ عَمْرٌو سَمِعْتُ جَابِرَ بْنَ عَبْدِ اللَّهِ ـ رضى الله عنهما ـ قَالَ قَالَ لَنَا رَسُولُ اللَّهِ صلى الله عليه وسلم يَوْمَ الْحُدَيْبِيَةِ ‏ "‏ أَنْتُمْ خَيْرُ أَهْلِ الأَرْضِ ‏"‏‏.‏ وَكُنَّا أَلْفًا وَأَرْبَعَمِائَةٍ، وَلَوْ كُنْتُ أُبْصِرُ الْيَوْمَ لأَرَيْتُكُمْ مَكَانَ الشَّجَرَةِ‏.‏ تَابَعَهُ الأَعْمَشُ سَمِعَ سَالِمًا سَمِعَ جَابِرًا أَلْفًا وَأَرْبَعَمِائَةٍ‏.‏
Reference : Sahih al-Bukhari 4154
In-book reference : Book 64, Hadith 198
USC-MSA web (English) reference : Vol. 5, Book 59, Hadith 475
  (deprecated numbering scheme)