(18) باب اسْتِحْبَابِ مُبَايَعَةِ الإِمَامِ الْجَيْشَ عِنْدَ إِرَادَةِ الْقِتَالِ وَبَيَانِ بَيْعَةِ الرِّضْوَانِ تَحْتَ الشَّجَرَةِ
The same tradition has been handed down through a different chain of transmitters.
Reference: Sahih Muslim 1857 b
In-book reference: Book 33, Hadith 113
USC-MSA web (English) reference(deprecated numbering scheme): Book 20, Hadith 4585