Sahih Bukhari Volume 5, Book 58, Hadith Number 229.

Narated By ‘Abdullah bin Ka’b : Who was Kab’s guide when Ka’b turned blind: I heard Ka’b bin Malik narrating: When he remained behind (i.e. did not Join) the Prophet in the Ghazwa of Tabuk. Ibn Bukair, in his narration stated that Ka’b said, ” I witnessed the Al-‘Aqaba pledge of allegiance at night with the Prophet when we jointly agreed to support Islam with all our efforts I would not like to have attended the Badr battle instead of that ‘Aqaba pledge although Badr is more well-known than it, amongst the people.”