Musannaf Ibn Abi Shayba 37:402

Abu Usama narrated to us, he said: Hisham bin Urwah narrated to us, from Fatimah bint al-Mundhir, from Asma, who said: I came to Aisha, and the people were standing, and she was praying. I said: "What is the matter with the people?" She gestured with her hand toward the sky, or she said: "Subhan Allah." I said: "A sign?" She gestured with her head: "Yes." The Messenger of Allah (ﷺ) prolonged [the prayer], until I began to feel faint, and I started pouring water over my head. She said: Then the Messenger of Allah (ﷺ) praised Allah and extolled Him as He deserves, and said: "There is nothing that I had not seen before except that I have seen it in this place of mine, even Paradise and Hell." "And it has been revealed to me that you will be tested in the graves, like—or near to—I do not know which of the two she said—the trial of the Dajjal."