The Statement of Allah the Most High: "...When they gave their Bai'a (pledge) to you (O Muḥammad pbuh) under the tree..." (V.48:18)
حَدَّثَنَا قُتَيْبَةُ بْنُ سَعِيدٍ، حَدَّثَنَا سُفْيَانُ، عَنْ عَمْرٍو، عَنْ جَابِرٍ، قَالَ كُنَّا يَوْمَ الْحُدَيْبِيَةِ أَلْفًا وَأَرْبَعَمِائَةٍ.
Narrated Jabir: We were one thousand and four hundred on the Day of Al-Hudaibiya.