The same tradition has been handed down through a different chain of transmitters.
Sahih Muslim Book 33, Hadith 113
← Previous Hadith The Companions of the Tree (i e. those who swore fealty under the tree) were one thousand and three hundred, and the people of Aslam tribe were one-eighth of the Muhajirs.

Sahih Muslim Book 33, Hadith 112 Next Hadith → I remember being present on the Day of the Tree, and the Prophet (ﷺ) was taking the oath of the people and I was holding a twig of the tree over his head. We were fourteen hundred (in number). We did not take oath to the death, but to the effect that we would not run away from the battlefield.

Sahih Muslim Book 33, Hadith 114