فٳن حاجوك
So if they dispute with you (Muhammad),
so if they argue with you about Tawhid.
فقل أسلمت وجهي لله ومن اتبعن
Say: "I have submitted myself to Allah (in Islam), and (so have) those who follow me.''
meaning, Say, `I have made my worship sincere for Allah Alone without partners, rivals, offspring or companion,
ومن اتبعن
(and those who follow me) who followed my religion and embraced my creed.'
In another Ayah, Allah said,
قل هذه سبيلى أدعو إلى الله على بصيرة أنا ومن اتبعنى
Say (O Muhammad): "This is my way; I invite unto Allah with sure knowledge, I and whosoever follows me...'' (12:108)
Islam is the Religion of Mankind and the Prophet Was Sent to all Mankind
Allah commanded His servant and Messenger, Muhammad, to call the People of the Two Scriptures and the unlettered idolators to his religion, way, Law and all that Allah sent him with.
Allah said,
وقل للذين أوتوا الكتاب واﻻميين أأسلمتم فٳن أسلموا فقد اهتدوا وإن تولوا فٳنما عليك البﻼغ
And say to those who were given the Scripture (Jews and Christians) and to those who are illiterates (Arab pagans): "Do you (also) submit yourselves!'' If they do, they are rightly guided; but if they turn away, your duty is only to convey the Message.
meaning, their reckoning is with Allah and their return and final destination is to Him. It is He Who guides whom He wills and allows whom He wills to stray, and He has the perfect wisdom and the unequivocal proof for all of this.
This is why Allah said,
والله بصير بالعباد
And Allah sees the servants.
for He has perfect knowledge of who deserves to be guided and who does not deserve to be guided. Verily,
ﻻ يسٲل عما يفعل وهم يسٲلون
(He cannot be questioned for what He does, while they will be questioned) (21:23) because of His perfect wisdom and mercy.
This and similar Ayat are clear proofs that the Message of Muhammad is universal to all creation, as it is well established in the religion, according to the various texts of the Book and Sunnah. For instance, Allah said,
قل يٲيها الناس إنى رسول الله إليكم جميعا
Say (O Muhammad): "O mankind! Verily, I am sent to you all as the Messenger of Allah.'' (7:158)
and,
تبارك الذى نزل الفرقان على عبده ليكون للعلمين نذيرا
Blessed be He Who sent down the criterion to His servant that he may be a warner to the Alamin (mankind and Jinn). (25:1)
The Two Sahihs and other collections of Hadith recorded that;
the Prophet sent letters to the kings of the earth during his time and to different peoples, Arabs and non-Arabs, People of the Book and the unlettered, just as Allah had commanded him.
Abdur-Razzaq recorded that Ma`mar said, that Hammam said that Abu Hurayrah said that the Prophet said,
والذي نفسي بيده ﻻ يسمع بي أحد من هذه اﻻمة يهودي وﻻ نصراني ومات ولم يومن بالذي أرسلت به إﻻ كان من أهل النار
By He in Whose Hand is my soul! No member of this Ummah, no Jew or Christian, hears of me but dies without believing in what I was sent with, but will be among the people of the Fire.
Muslim recorded this Hadith.
The Prophet said,
بعثت إلى اﻻحمر واﻻسود
I was sent to the red and black.
and,
كان النبي يبعث إلى قومه خاصة وبعثت إلى الناس عامة
A Prophet used to be sent to his people, but I was sent to all mankind