Narrations about Imam Mahdi (as) in Sahih Muslim

Please read the narartion in Sahih Muslim which shows:

The Holy Prophet said:

" there would be a caliph in the last (period) of my Ummah who would freely give handfuls of wealth to the people without counting it. I said to Abu Nadra and Abu al-'Ala: Do you mean 'Umar b. 'Abd al-Aziz? They said: No (he would be Imam Mahdi).

http://sunnah.com/urn/269610

Signs about Imam Mahdi (as) in Sahih Muslim

There are well known signs about Imam Mahdi's re-appearance in Shia Sunni books. When Imam Mahdi (as) will show himself in Mecca. A group of army would be sent to fight with him. When that group of army will reach outside Medina to a plain ground, the army would be sunk in the ground.

This is one of the proven sign of 12th Imam Mahdi (as).

Some people got confuse with this narration that it is about Ibn e Zubair but the narrator told this narration is not about Ibn e Zaubair army, Abdullah b. Safwan said: By God, it does not imply this army.

http://sunnah.com/urn/268890

Please read another narration.

http://sunnah.com/urn/268880