صَحِيحُ مُسْلِمٍ
Sahih Muslim 1858 b
The Book on Government
It is recommended for the army to swear allegiance to the ruler when intending to fight, and an account of Bay'at Ar-Ridwan beneath the tree
وَحَدَّثَنَاهُ يَحْيَى بْنُ يَحْيَى، أَخْبَرَنَا خَالِدُ بْنُ عَبْدِ اللَّهِ، عَنْ يُونُسَ، بِهَذَا الإِسْنَادِ.
This hadith has been narrated on the authority of Yunus with the same chain of transmitters.
Sahih Muslim, 1858 bSahihصحيح