Praise be to Allah, and peace and blessings be upon the Messenger of Allah. To proceed:
The two testimonies of faith—testifying that there is no deity worthy of worship except Allah and that Muhammad ﷺ is the Messenger of Allah—are the foundation of entering Islam and among its greatest symbols.
A person enters Islam by affirming the oneness of Allah and believing in the message of Prophet Muhammad ﷺ, along with pronouncing the two testimonies if he is physically able to speak.
As for the complete phrase “There is no deity worthy of worship except Allah, Muhammad is the Messenger of Allah” appearing together in this exact wording in one place, it does not occur in the Qur’an in this combined form. However, each of the two testimonies appears clearly and explicitly in the Qur’an, and the Prophetic Sunnah combines them together.
The first testimony is explicitly mentioned in several places in the Qur’an.
Allah Almighty says:
“So know that there is no deity except Allah, and ask forgiveness for your sin.”
[Muhammad 47:19]
Allah also says:
“Allah bears witness that there is no deity except Him, and so do the angels and those of knowledge, maintaining creation in justice. There is no deity except Him, the Almighty, the All-Wise.”
[Aal ‘Imran 3:18]
This testimony is the foundation of Tawhid. Its meaning is that Allah alone deserves worship, so no act of worship should be directed to anyone other than Him.
It is not merely a matter of pronouncing words with the tongue. Rather, a person must believe in their meaning and accept what they require: worshipping Allah Almighty alone.
The testimony that Prophet Muhammad ﷺ is the Messenger of Allah is also stated very clearly.
Allah says:
“Muhammad is the Messenger of Allah, and those with him are firm against the disbelievers and merciful among themselves.”
[Al-Fath 48:29]
This verse contains the exact phrase:
“Muhammad is the Messenger of Allah.”
Allah also says:
“Muhammad is not the father of any of your men, but he is the Messenger of Allah and the Seal of the Prophets.”
[Al-Ahzab 33:40]
Allah also commanded all people to believe in the Prophet’s ﷺ message and follow him:
“Say, ‘O mankind, indeed I am the Messenger of Allah to you all… So believe in Allah and His Messenger, the unlettered Prophet who believes in Allah and His words, and follow him so that you may be guided.’”
[Al-A‘raf 7:158]
Thus, the Qur’an does not merely affirm that Muhammad ﷺ is the Messenger of Allah; it also commands people to believe in him and follow him.
It is not necessary for every foundation of religion to be gathered in a single sentence or verse in order for it to be obligatory.
The Qur’an clearly establishes that there is no deity except Allah, and clearly establishes that Muhammad is the Messenger of Allah, and it commands belief in Allah and His Messenger and obedience to them.
As for combining the two testimonies into one formula as the key to entering Islam, this is explicitly established in the authentic Sunnah.
The Prophet ﷺ said:
“I have been commanded to fight the people until they testify that there is no deity except Allah and that Muhammad is the Messenger of Allah, establish the prayer, and give zakah…”
Narrated by Al-Bukhari and Muslim.
Here, the Prophet ﷺ explicitly combined the two testimonies.
When the Prophet ﷺ sent Mu‘adh ibn Jabal (may Allah be pleased with him) to Yemen, he instructed him to begin by calling people to the foundation of Islam.
He ﷺ said:
“Call them to testify that there is no deity except Allah and that I am the Messenger of Allah.”
Narrated by Al-Bukhari and Muslim.
Then, after they accepted that, he instructed him to teach them prayer and zakah.
This shows that affirming Tawhid and the messengership of Muhammad ﷺ is the beginning by which a person enters Islam, after which he learns the remaining obligations and rulings.
Because belief in Allah includes accepting His messengers and not rejecting them. After Allah sent Muhammad ﷺ to all humanity, belief in his message and following him became part of what belief in Allah requires.
Allah says:
“So believe in Allah and His Messenger.”
[Al-A‘raf 7:158]
Allah also says:
“O you who believe, believe in Allah and His Messenger and the Book which He sent down upon His Messenger.”
[An-Nisa 4:136]
It is therefore not valid for a person to say, “I believe in Allah,” while rejecting the messenger whom Allah sent to him.
Testifying that Muhammad is the Messenger of Allah includes believing what he informed us of, obeying what he commanded, and following the law he brought.
No, because both the Qur’an and the Sunnah are fundamental sources of Islamic legislation, and the Qur’an itself commands obedience to the Messenger ﷺ.
Allah says:
“Whoever obeys the Messenger has indeed obeyed Allah.”
[An-Nisa 4:80]
Allah also says:
“Whatever the Messenger gives you, take it; and whatever he forbids you from, refrain from it.”
[Al-Hashr 59:7]
Therefore, it is not necessary to find every detail of worship or religion gathered in its exact wording in a single verse, as long as it is established by the Qur’an and the authentic Sunnah.
The complete phrase “There is no deity worthy of worship except Allah, Muhammad is the Messenger of Allah” does not appear in the Qur’an as one combined phrase in a single verse.
However, the Qur’an clearly mentions both testimonies.
Allah says:
“So know that there is no deity except Allah.”
[Muhammad 47:19]
And He says:
“Muhammad is the Messenger of Allah.”
[Al-Fath 48:29]
As for combining them as the two testimonies by which a person enters Islam, this is explicitly established in authentic hadiths from the Prophet ﷺ.
Therefore, the two testimonies were not an expression invented by Muslims after the Prophet ﷺ. Rather, their foundations are established in the Qur’an, while their combination and their role in entering Islam are established in the authentic Sunnah.
And Allah knows best.