It was narrated that Yazid bin Abi 'Ubaid said:

"I said to Salamah bin Al-Akwa': 'What pledge did you make to the Prophet on the Day of Al-Hudaibiyyah?' He said: 'For death."'

أَخْبَرَنَا قُتَيْبَةُ، قَالَ حَدَّثَنَا حَاتِمُ بْنُ إِسْمَاعِيلَ، عَنْ يَزِيدَ بْنِ أَبِي عُبَيْدٍ، قَالَ قُلْتُ لِسَلَمَةَ بْنِ الأَكْوَعِ عَلَى أَىِّ شَىْءٍ بَايَعْتُمُ النَّبِيَّ ﷺ يَوْمَ الْحُدَيْبِيَةِ قَالَ عَلَى الْمَوْتِ .