Language:
كتاب الأحكام
93  
Judgments (Ahkaam)
(43)
Chapter: How do the people give the Bai'a to the Imam
(43)
باب كَيْفَ يُبَايِعُ الإِمَامُ النَّاسَ
Sahih al-Bukhari 7203

Narrated `Abdullah bin Dinar:

I witnessed Ibn `Umar when the people gathered around `Abdul Malik. Ibn `Umar wrote: I gave the Pledge of allegiance that I will listen to and obey Allah's Slave, `Abdul Malik, Chief of the believers according to Allah's Laws and the Traditions of His Apostle as much as I can; and my sons too, give the same pledge.'

حَدَّثَنَا مُسَدَّدٌ، حَدَّثَنَا يَحْيَى، عَنْ سُفْيَانَ، حَدَّثَنَا عَبْدُ اللَّهِ بْنُ دِينَارٍ، قَالَ شَهِدْتُ ابْنَ عُمَرَ حَيْثُ اجْتَمَعَ النَّاسُ عَلَى عَبْدِ الْمَلِكِ ـ قَالَ ـ كَتَبَ إِنِّي أُقِرُّ بِالسَّمْعِ وَالطَّاعَةِ لِعَبْدِ الْمَلِكِ أَمِيرِ الْمُؤْمِنِينَ عَلَى سُنَّةِ اللَّهِ وَسُنَّةِ رَسُولِهِ مَا اسْتَطَعْتُ، وَإِنَّ بَنِيَّ قَدْ أَقَرُّوا بِمِثْلِ ذَلِكَ‏.‏
Reference : Sahih al-Bukhari 7203
In-book reference : Book 93, Hadith 63
USC-MSA web (English) reference : Vol. 9, Book 89, Hadith 310
  (deprecated numbering scheme)