Allah the Exalted and Most Honored honors, regards and praises His Messenger 
by saying,
[إِنَّ الَّذِينَ 
يُبَايِعُونَكَ إِنَّمَا يُبَايِعُونَ اللَّهَ]
(Verily, those who give pledge to you, they are giving pledge to Allah.) 
Allah the Exalted and Most High said in another Ayah,
[مَّنْ يُطِعِ 
الرَّسُولَ فَقَدْ أَطَاعَ اللَّهَ]
(He who obeys the Messenger, has indeed obeyed Allah.) (4:80) Allah said, 
next,
[يَدُ اللَّهِ فَوْقَ 
أَيْدِيهِمْ]
(The Hand of Allah is over their hands.) meaning, He is with them, hearing 
their statements and witnessing their stand, having full knowledge of them 
inwardly and outwardly. Therefore, Allah the Exalted was indeed taking the 
pledge from them through His Messenger ,
[إِنَّ اللَّهَ 
اشْتَرَى مِنَ الْمُؤْمِنِينَ أَنفُسَهُمْ وَأَمْوَلَهُمْ بِأَنَّ لَهُمُ 
الّجَنَّةَ يُقَـتِلُونَ فِى سَبِيلِ اللَّهِ فَيَقْتُلُونَ وَيُقْتَلُونَ وَعْدًا 
عَلَيْهِ حَقًّا فِي التَّوْرَاةِ وَالإِنجِيلِ وَالْقُرْءانِ وَمَنْ أَوْفَى 
بِعَهْدِهِ مِنَ اللَّهِ فَاسْتَبْشِرُواْ بِبَيْعِكُمُ الَّذِى بَايَعْتُمْ بِهِ 
وَذَلِكَ هُوَ الْفَوْزُ الْعَظِيمُ ]
(Verily, Allah has purchased of the believers their lives and their 
properties for which theirs shall be the Paradise. They fight in Allah's cause, 
so they kill and are killed. It is a promise in truth, binding on Him in the 
Tawrah and the Injil and the Qur'an. And who is truer to his covenant than Allah 
Then rejoice in the bargain you have concluded. That is the supreme 
success.)(9:111) Allah said,
[وَمَنْ أَوْفَى 
بِمَا عَـهَدَ عَلَيْهِ اللَّهَ فَسَيُؤْتِيهِ أَجْراً عَظِيماً]
(...and whosoever fulfills what the covenants he makes with Allah, He will 
bestow on him a great reward.) a generous reward. The pledge mentioned here is 
the pledge of Ar-Ridwan which was pledged under a tree, a Samurah, in the area 
of Al-Hudaybiyyah. The number of the Companions who gave their pledge to Allah's 
Messenger at that time was either 1,300, 1,400 or 1,500. However, 1,400 is the 
better choice.