Sahih Muslim Book 41, Hadith Number 6889.

Chapter : The sinking of an army in the earth which would attack the House.

Abdullah b. Safwan reported the Mother of the Faithful as saying that Allah’s Messenger (may peace be upon him) said: They would soon seek protection in this House, viz. Ka’ba (the defenceless), people who would have nothing to protect themselves in the shape of weapons or the strength of the people. An army would be sent to fight (and kill) them and when they would enter a plain ground the army would be sunk in it. Yusuf (one of the narrators) said: It was a people of Syria (hordes of Hajjaj) who had been on that day coming towards Mecca for an attack (on ‘Abdulllah b. Zubair) and Abdullah b. Safwan said: By God, it does not imply this army.