The Muslims are obliged to live in one State, and be ruled by one Khalifah. It is forbidden for the Muslims in the world to have more than one State and more than one Khalifah. .

It is also necessary that the ruling system in the Khilafah State be a system of unity, and it is forbidden for it to be a federal system. .

This is due to what Muslim narrated on the authority of Abdullah b. Amru b. al- Aas who reported that he heard the Messenger of Allah (P.B.U.H) say: .

"Whoever pledged allegiance to an Imam giving him the clasp of his hand and the fruit of his heart, he should obey him as much as he can, and if another comes to dispute with him, you must strike the neck of the latter". .

It has also been narrated by Muslim that Afrajah said: “I heard the Messenger of Allah (P.B.U.H) say: .

"Whoever comes to you while your affair has been united over one man, intending to divide your power or dissolve your unity, kill him".” [Muslim, Sahih, #1844] .

It has also been reported by Muslim from Abu Said Al Khudri that the Messenger of Allah (P.B.U.H) said: .

"If the Oath of Allegiance (bayah) has been taken for two Khalifahs, kill the latter of them." [Muslim, Sahih, #1853] .

Muslim also reported that Abu Hazim said, “I accompanied Abu Huraira for five years and heard him talking about the Prophet’s (P.B.U.H) saying: .

"The children of Israel have been governed by Prophet; whenever a Prophet died another Prophet succeeded him; but there will be no Prophet after me. There will soon be Khulafaa and they will number many; they asked: What then do you order us? .

He (P.B.U.H) said: Fulfil allegiance to them one after the other, and give them their dues; for verily Allah will ask them about what he entrusted them with".”[Bukhari, Sahih, #3455] ..