حَدَّثَنَا قُتَيْبَةُ، حَدَّثَنَا حَاتِمُ بْنُ إِسْمَاعِيلَ، عَنْ يَزِيدَ بْنِ أَبِي عُبَيْدٍ، قَالَ قُلْتُ لِسَلَمَةَ بْنِ الأَكْوَعِ عَلَى أَىِّ شَيْءٍ بَايَعْتُمْ رَسُولَ اللَّهِ صلى الله عليه وسلم يَوْمَ الْحُدَيْبِيَةِ قَالَ عَلَى الْمَوْتِ ‏.‏ هَذَا حَدِيثٌ حَسَنٌ صَحِيحٌ ‏.‏

Narrated Yazid bin Abi 'Ubaid: "I said to Salamah bin Al-Akwa': "For what did you pledge to the Messenger of Allah (PBUH) on the Day of Al-Hudaibiyyah?" He said: "For death." This Hadith is Hasan Sahih. Translation Not Available

Book Ref: Jamiya Tirmidhi Book 21 Hadith 1592
Web Ref:  Jamiya Tirmidhi Vol 3 Book 19 Hadith 1592