We were one thousand and four hundred on the Day of Al-Hudaibiya.  

كُنَّا يَوْمَ الْحُدَيْبِيَةِ أَلْفًا وَأَرْبَعَمِائَةٍ  

On the day of Al-Hudaibiya, Messenger of Allah 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."  

لَنَا رَسُولُ اللَّهِ ﷺ يَوْمَ الْحُدَيْبِيَةِ أَنْتُمْ خَيْرُ أَهْلِ الأَرْضِ وَكُنَّا أَلْفًا وَأَرْبَعَمِائَةٍ وَلَوْ كُنْتُ أُبْصِرُ الْيَوْمَ لأَرَيْتُكُمْ مَكَانَ الشَّجَرَةِ  

We were one thousand and four hundred on the Day of Al-Hudaibiya. (Using translation from Bukhārī 4840)  

كُنَّا يَوْمَ الْحُدَيْبِيَةِ أَلْفًا وَأَرْبَعَ مِائَةٍ فَقَالَ لَنَا رَسُولُ اللهِ ﷺ أَنْتُمُ الْيَوْمَ خَيْرُ أَهْلِ الْأَرْضِ  

"عَنِ الْبَرَاءِ قَالَ: كُنَّا يَوْمَ الْحُدَيْبِيَةِ أَلْفًا وَأَرْبَعَمِائَةٍ".