"And this Qur'aan is not such as could ever be produced by other than Allaah (Lord of the heavens and the earth), but (on the contrary), it is a confirmation of (revelation) that was before it [i.e. the Tauraat (Torah), and the Injeel (Gospel), etc.] and a full explanation of the Book (i.e. laws and orders, etc, decreed for mankind) - wherein there is no doubt - from the the Lord of the Al-'Alameen (mankind and jinns and all that exists)." (V.10:37)

"And whoever seeks a religion other than Islaam, it will never be accepted of him, and in the Hereafter he will be one of the losers." (V.3:85)

Narrated Aboo Hurairah (radiAllaahu 'anhu): The Prophet (sal-Allaahu 'alayhe wa sallam) said,

"There was no Prophet among the Prophets but was given miracles because of which people had security or had belief, but what I have been given is the Divine Inspiration which Allaah has revealed to me. So I hope that my followers will be more than those of any other Prophet on the Day of Resurrection." [Hadeeth No. 379, Vol. No. 9, Saheeh Al-Bukhaaree]

Narrated Jaabir bin 'Abdullaah (radiAllaahu 'anhuma),

Some angels came to the Prophet (Muhammad sal-Allaahu 'alayhe wa sallam) while he was sleeping. Some of them said, "He is sleeping." Others said, "His eyes are sleeping but his heart is awake." Then they said, "There is an example for this companion of yours." One of them said, "Then set forth an exapmle for him." One of them said, "He is sleeping." Another siad, "His eyes are sleeping but his heart is awake." Then they said, "His example is that of aman who build a house and then offered therein a banquet and sent an inviter (messenger) to invite the people. So whoever accepted the invitation of the inviter, entered the house and ate of the banquet, and whoever did not accept the invitation of the inviter, did not enter the house, nor did he eat of the banquet." Then the angels said, "Interpret this parable to him so that he may understand it." One of them said, "He is sleeping." The others said, "his eyes are sleeping but his heart is awake." And then they said, "The house stands for Paradise and the callmaker is Muhammad (sal-Allaahu 'alayhe wa sallam) and whoever obeys Muhammad, obeys Allah; and whoever disobeys Muhammad, disobeys Allah. Muhammad separated the people (i.e., through his message, the good is distinguished from the bad, and the believers from the disbelievers)." [Hadeeth No. 385, Vol. No. 9, Saheeh Al-Bukhaaree]

Narrated Aboo Hurairah (radiAllaahu 'anhu): The Prophet (sal-Allaahu 'alayhe wa sallam) said,

"Both in this world and in the Hereafter, I am the nearest of all the people to 'Iesa (Jesus), the son of Maryam (Mary). The Prophets are paternal brothers; their mothers are different, but their religion is one (i.e., Islaamic Monotheism)." [Hadeeth No. 652, Vol. No. 4, Saheeh Al-Bukhaaree]

It is obligatory to have belief in the Messengership of the Prophet (Muhammad sal-Allaahu 'alayhe wa sallam).

Narrated Aboo Hurairah (radiAllaahu 'anhu): The Prophet (sal-Allaahu 'alayhe wa sallam) said,

"By Him (Allaah) in Whose Hand Muhammad's soul is, there is none from amongst the Jews and the Christians (of these present nations) who hears about me and then dies without believing in the Message with which I have been sent (i.e., Islaamic Monotheism), but he will be from the dwellers of the (Hell) Fire." [Saheeh Muslim, the Book of Faith, Vol. 1, Chapter No. 24] [See also (V.3:116)]