Sayyiduna Abdullah bin Zayd (may Allah be pleased with him) relates that at the time of (the battle of) al-Harrah, a man came and said: "There is so-and-so, taking the pledge of allegiance from people." He asked: "On what?" He replied: "On death." He said: "After the Messenger of Allah (peace and blessings be upon him), I will not pledge allegiance to anyone on this."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب قتال أهل البغي / 16561