Mukhtasar Muslim

It is narrated from Muhammad bin Munkadir that: I saw Sayyiduna Jabir bin Abdullah (may Allah be pleased with him) swearing an oath that Ibn Sayyad is the Dajjal. I said, "Do you swear by Allah?" He said, "I saw Sayyiduna Umar (may Allah be pleased with him) that he swore about this in the presence of the Messenger of Allah (peace and blessings be upon him), and he (the Prophet) did not deny it."