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

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."' Translation Not Available

Book reference: Sunan An Nisai Book 39 Hadith 4159
Web reference: Sunan An Nisai Volume 5 Book 39 Hadith 4164