Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) narrates: "That I should swear nine times that Ibn Sayyad is the Dajjal is dearer to me than that I should swear once to the contrary; and that I should swear nine times that the Messenger of Allah (peace and blessings be upon him) was killed as a martyr is dearer to me than that I should swear once that he was not killed; for Allah, the Mighty and Majestic, made him a Prophet and granted him the rank of a martyr."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 10083