Zuhri reported,

Abu Saeed Khudri reported that the Messenger of Allah ﷺ once told them a long hadith about Dajjal. Among the things he told them, he said, "He will come, but it is forbidden for him to enter the mountain passes of Madinah. So he will halt at some of the salt flats bordering Madinah, and on that day a man will go out to him who is the best of people, or among the best of people.The man will say to him, "I bear witness that you are Dajjal, the one the Messenger of Allah ﷺ told us about."Dajjal will say, "Tell me, if I kill this man and then bring him back to life, will you still have any doubt about the matter?"They will say, "No."So he will kill him and then bring him back to life. And when he revives him, the man will say, "By Allah, I have never seen you more clearly than I do now."Then Dajjal will want to kill him, but he will be given no power over him.Abu Ishaq said, "It is said that this man is Khidr ."

و حدثني عبد الله بن عبد الرحمن الدارمي أخبرنا أبو اليمان أخبرنا شعيب عن الزهري في هذا الإسناد بمثله