Musnad Ahmad 1156:17

Jarir narrated to us, from Abd al-Aziz ibn Rufay’, from Ubayd Allah ibn al-Qibtiyya, who said: Al-Harith ibn Abi Rabi’ah and Abd Allah ibn Safwan entered upon Umm Salamah, and I was with them. They asked her about the army that will be swallowed by the earth, and that was during the days of Ibn al-Zubayr. Umm Salamah said: I heard the Messenger of Allah, peace and blessings of Allah be upon him, say: "A seeker of refuge will seek refuge in the House (the Kaaba), so Allah will send an army. When they are in a desert plain of the earth, they will be swallowed by it." I said: "O Messenger of Allah, what about the one who was brought out against his will?" He said: "He will be swallowed by the earth along with them, but he will be resurrected according to his intention on the Day of Resurrection." I mentioned that to Abu Ja’far, and he said: "It is the desert plain of Medina."