Allah Most High says, favouring His Servants (5:3): (Today I have perfected for you your Religion and completed My Favour upon you, and I am pleased with Islam as your Religion)

This noble verse is a proof for the completeness of the Shar'ah, its perfection, how it supplies everything needed by the creation, those about whom Allah sent down His Statement (51:56): (And I did not create the Jinn or mankind except to worship Me)

Ibn Kathr said about this verse, (Today I have perfected… ): "…

For this reason, Allah made him the Seal of the Prophets and sent him to both the Jinn and mankind. So there is no Halaal except he made it permissible, and no haraam except he prohibited it, and no Religion except what he legislated.

Everything the Messenger of Allah (sallAllahu 'alayhe wa sallam) informed us of is the truthful reality; he never lied nor can one find any contradictions, as Allah says (6:115): (And the Word of your Lord was completed, truthfully and fairly)

Meaning truthfully in its conveyance and fairly with regards to the orders and prohibitions found in it. So when He perfected the Religion for them, the favour was completed upon them…" [Tafseer Ibn Kathr v.2, p.19]

And as Tawfq wrote: "…So it is unimaginable for someone to come (after hearing this verse) and introduce something into the Shar'ah, because his addition would imply that Allah's work needed corrected, and that the Shar'ah is lacking. This idea contradicts what comes in the Book of Allah. So it is impossible for someone to add to what Allah legislated, except that it would be blameworthy…" [Al-Bid'ah wal-Masaalih Al-Mursalah, p.111]

The adherents of other religions are inwardly convinced of this, and for Allah is the praise, but many of them deny it, as Allah says (27:14): (And they rejected it wrongfully and arrogantly, even though they themselves were thoroughly convinced of it)

On the authority of Taariq bin Shihaab, who narrated that the Jews said to 'Umar (may Allah be pleased with him),

"You people recite verse in your Book; if that verse would have been revealed to us, we would have taken that day as an 'Ed!" So 'Umar asked them, "Which verse is that?" They said, (Today I have perfected for you your Religion and completed My Favor upon you…) So then 'Umar remarked, " By Allah I surely know the very day that verse was revealed to the Messenger of Allah (sallAllahu 'alayhe wa sallam), and even the time of day! It was revealed to the Messenger of Allah (sallAllahu 'alayhe wa sallam) the night of 'Arafah and it was Jumu'ah." [Al-Bukhaar and Muslim]

And verily the Messenger of Allah (sallAllahu 'alayhe wa sallam) said: "There was never any prophet before me except that he had the duty of directing his nation to every good he knew of, and warning them about every evil he knew of…" [Al-Bukhaar]

It was Abu Tharr Al-Ghifaar (radhiyAllahu 'anhu) who said that after the Messenger of Allah (sallAllahu 'alayhe wa sallam) had left them, there was not a single bird flapping its wings in the air, except that he (sallAllahu 'alayhe wa sallam) mentioned something about it to them.

He said that the Prophet (sallAllahu 'alayhe wa sallam) said: "There is nothing left that draws one closer to the Paradise and distances one from the Hellfire, except that it has been made clear for you." [Sahh, At-Tabaraan's Al-Mu'jamul-Kabr]

This hadth of the dignified Prophet (sallAllahu 'alayhe wa sallam) is a clear, unmistakable proof for that fact that he indeed explained every single thing that draws one close to the Paradise in great detail, and that there is no action that distances us from the Hellfire except that he (sallAllahhu 'alayhe wa sallam) clarified it for us.

So any invention or innovation is only an attempt to correct the Shar'ah, an ugly crime by which the criminal calls out, "The Shar'ah is not sufficient! It is not complete! It needs my invention!"

This is exactly what the Companions of the Messenger (sallAllahu 'alayhe wa sallam) understood, as it has been authentically reported that Ibn Mas'ud (radhiyAllahu 'anhu) said,

"Follow and do not innovate, for verily that is sufficient for you, and know that every innovation is misguidance." [An authentic report found in Abû Khaythamah's book Al-'Ilm (#54) by way of Ibraaheem An-Nakhaa', who said that 'Abdullaah bin Mas'ûd said it.]

To conclude, Al-Imaam Ash-Shaatib said: "…Verily those who try to make their innovations acceptable, they cling to their idea that the Shar'ah is constantly evolving. So they always manage to have their own personal way to explain away Allah's Statement, (Today I have perfected for you your Religion… )…" [Al-I'tisaam v.1, p.111]

He also said: "…If that is the case, then the innovator is only saying, "Verily the Shar'ah was not completed, there is something we must correct in it!" Because if he was certain about its completion and perfection from every angle, then he would not have innovated, he would have had no reason to follow after Allah's Shar'ah, correcting and adjusting it. So a person who says this is clearly far astray from the Straight Path. Ibn Al-Maajishûn said that he heard Al-Imaam Maalik saying,

'Whoever innovates anything in Islam, and views it as something good, he has accused Muhammad (sallAllahu 'alayhe wa sallam) of betraying the trust of messengership, because verily Allah Most High says, (Today I have perfected for you your Religion… ), so whatever was not part of the Religion that day, it is not part of the Religion today.'…" [Al-I'tisaam v.1, p.49]

As Al-Ma'sum said: "…So the various ways of proper, correct worship found in the Religion have been made clear by the One who created all of the creation, through the tongue of His Messenger Muhammad (sallAllahu 'alayhe wa sallam). So whoever adds anything or takes anything away stands (with his assembly of traditions from his own self) in direct opposition to the All-Wise, All-Knowing Creator. So perhaps his medicine will be his sickness, his worship will be punishable disobedience, and he will not even detect it. For verily the Religion has been completed perfectly, and the one who adds to it assumes it is lacking, so he comes to make it better with his corrupt intellect, his stagnant arrogance…" [Miftaah Al-Jannah Laa Ilaaha IllAllah with 'Al Hasan's tahqq, p.58 ]

Al-Imaam Ash-Showkaan said, in a discussion with some innovators, refuting their opinions:

"…Since Allah completed His Religion before taking the life of His Prophet (sallAllahu 'alayhe wa sallam), what are these ideas his nation comes up with after his Lord completed His Religion?!?! If they are saying that this new matter is part of the Religion, then they are saying the Religion was not complete except with the addition of their idea, therefore in their belief is a rejection of the Qur'aan! And if they say that the new matter is not part of the Religion, then what benefit is there in occupying yourself with things not found in the Religion?!?! And this is an awesome proof, and a magnificent piece of evidence! No follower of opinions can ever refute it, so make this honourable verse the first thing you strike the faces of the people of opinions with, and force their reluctant noses to it, and disprove all of their arguments with it…" [Al-Qowl Al-Mufd p.38]

Because, as it is said, "Everything invented after the revelation of this verse is an unwanted surplus, an undesirable excess, a cursed innovation." [Sayr A'laam An-Nubalaa', v.18, p.509]