Salama said, "I gave the Pledge of allegiance (Al-Ridwan) to Allah's Messenger (ﷺ) and then I moved to the shade of a tree. When the number of people around the Prophet (ﷺ) diminished, he said, 'O Ibn Al-Akwa` ! Will you not give to me the pledge of Allegiance?' I replied, 'O Allah's Messenger (ﷺ)! I have already given to you the pledge of Allegiance.' He said, 'Do it again.' So I gave the pledge of allegiance for the second time." I asked 'O Abu Muslim! For what did you give he pledge of Allegiance on that day?" He replied, "We gave the pledge of Allegiance for death."
Sahih al-Bukhari Book 56, Hadith 171
← Previous Hadith that in the time (of the battle) of Al-Harra a person came to him and said, "Ibn Hanzala is taking the pledge of allegiance from the people for death." He said, "I will never give a pledge of allegiance for such a thing to anyone after Allah's Messenger (ﷺ)."

Sahih al-Bukhari Book 56, Hadith 170 Next Hadith → On the day (of the battle) of the Trench, the Ansar were saying, "We are those who have sworn allegiance to Muhammad for Jihaid (for ever) as long as we live." The Prophet (ﷺ) replied to them, "O Allah! There is no life except the life of the Hereafter. So honor the Ansar and emigrants with Your Generosity."

Sahih al-Bukhari Book 56, Hadith 172