Abbas - Tanwîr al-Miqbâs min Tafsîr Ibn ‘Abbâs
When they said to the Prophet (pbuh) bring us a witness to testify that you are a prophet, Allah said: (Say) to them, O Muhammad: (What thing is of most weight) that is, fairer and most pleasing (in testimony?) If they answer, fine, if not (Say: Allah is witness between you and me) that I am His Messenger and this Qur'an is His speech. (And this Qur'an hath been inspired in me) and that Gabriel has brought down this Qur'an to me, (that I may warn therewith you) with the Qur'an (and whomsoever it may reach) I am a warner to him. (Do ye) O people of Mecca (in sooth bear witness that there are gods beside Allah) i.e. idols: you say that they are Allah's daughters? And if they bear witness, (Say: I bear no such witness) with you. (Say) O Muhammad: (He is only One God) the true God is only One God. (Lo! I am innocent of that which you associate (with Him)) of idols in worship.
Say: “What thing is greater in bearing witness?” Say: “God.”
There is no bearing witness more truthful than the Real's own bearing witness to what He witnessed at the first. That is His words, “God bears witness that there is no god but He” [3:18]. This is the Real's bearing witness that the Real is the Real.
On the first day, at the beginningless covenant, with true words and pure speech, He reported of the unitary existence, the self-sufficient being, the endless majesty, the eternal beauty, the continuous Essence, and the self-standing attributes.
Abū ʿAbdallāh Qurashī said, “This is a teaching for the servants and a right guidance for the seekers. With His own gentleness He is teaching the servants to bear witness in their measure to His oneness and solitariness, just as He bears witness as is fitting for Him. Put aside the path of resistance, lest you fall into the pit like the abandoned Iblis.”
One of them said, “God bears witness to His oneness, His unity, and His self-sufficiency. Others, like the angels and the possessors of knowledge, bear witness by assenting to the truth of that to which He bears witness concerning Himself.”
He Himself bore witness to His lordhood, greatness, and oneness, for no one else was worthy of bearing witness. The creatures cannot reach the core of His majesty and tremendousness, and their bearing witness is nothing but assenting to the truth of the Real's bearing witness.
Jaʿfar ibn MuḤammad said, “The bearing witness of people is built on four pillars: first following the commands, second avoiding prohibitions, third contentment, and fourth approval.”
It is said that people's bearing witness is of three sorts: the bearing witness of the common people, the bearing witness of the elect, and the bearing witness of the elect of the elect. The bearing witness of the common people is to emerge from associationism. The bearing witness of the elect is to enter into contemplation. The bearing witness of the elect of the elect is the breeze of companionship from the side of proximity for the sake of union.
The self-purifier sees all from Him, the recognizer sees all in Him, the tawḤīd-voicer sees all as He. Every named being is a loan. True being is He-the rest are suspect.
Say “God,” then leave them [6:91]. Oh, all is You, and that's it! How could anyone appear alongside You?
When they said to the Prophet (s), ‘Bring us someone to testify to the truth of your prophethood, for the People of the Scripture have denied you’, the following was revealed: Say, to them: ‘What thing is greatest in testimony?’ (shahādatan: this is for specification, and is derived from the [implied] subject of the sentence). Say: ‘God — even if they do not say this, there is no other response — He, is Witness between me and you, to my truthfulness; and this Qur’ān has been revealed to me that I may warn you, [that I may] make you fear, O people of Mecca, thereby, and whomever it may reach (wa-man balagha: this is a supplement to the [suffixed] pronoun [‘you’] of undhira-kum, ‘I may warn you’), that is to say, whomever among men and jinn the Qur’ān may reach. Do you indeed bear witness that there are other gods with God?’ (this interrogative is meant as a disavowal). Say, to them: ‘I do not bear witness’, to this. Say: ‘He is only One God, and I am innocent of what you associate’, with Him of idols.
(Whatever mercy, Allah may grant to mankind, none can withhold it, and whatever He may withhold, none can grant it thereafter) 35:2. It is recorded in the Sahih that the Messenger of Allah used to supplicate,
(O Allah, there is none Who can avert what You grant or give what You deprive, and no fortune ever helps the fortunate against You.) This is why Allah said,
وَهُوَ الْقَاهِرُ فَوْقَ عِبَادِهِ
(And He is the Irresistible, above His servants,) meaning, to Him the necks are subservient, the tyrants humble before Him and He has complete control over all things. The creatures have all bowed to Allah and are humbled before His grace, honor, pride, greatness, highness and ability over all things. The creatures are insignificant before Him, for they are all under His irresistible decision and power,
(and He is the All-Wise,) in all His actions,
(Well-Acquainted with all things.) Who places everything in its rightful place, grants and favors whomever deserves His favor. Allah said next,
قُلْ أَىُّ شَىْءٍ أَكْبَرُ شَهَـدةً
(Say: "What thing is the most great in witness'') or what is the greatest witness,
قُلِ اللَّهِ شَهِيدٌ بِيْنِى وَبَيْنَكُمْ
(Say: "Allah (the Most Great!) is Witness between you and I'') for He knows what I brought you and what you will answer me with,
(But those of the sects that reject it, the Fire will be their promised meeting place.) 11:17 Ar-Rabi` bin Anas said, "Those who follow the Messenger of Allah ought to call to what the Messenger of Allah called to and warn against what he warned against.'' Allah said next,
(Say: "Only He is God, alone, and truly I am innocent of what you join in worship with Him.'')
People of the Book Recognize the Prophet Just as They Recognize Their Own Children
Allah says, the People of the Book know what you brought them, O Muhammad, as they know their own children. This is because they received good news from the previous Messengers and Prophets about the coming of Muhammad, his attributes, homeland, his migration, and the description of his Ummah. Allah said next,
الَّذِينَ خَسِرُواْ أَنفُسَهُم
(Those who have lost (destroyed) themselves) and thus incurred the ultimate loss,
فَهُمْ لاَ يُؤْمِنُونَ
(will not believe.) in this clear matter. A matter about which the previous Prophets gave good news, and a matter extolled about in ancient and modern times. Allah said next,
(And who does more wrong than he who invents a lie against Allah or rejects His Ayat) meaning, there is no person more unjust than he who lies about Allah and claims that Allah has sent him, while Allah did not send him. There is no person more unjust than he who denies Allah's proofs, signs and evidences,
إِنَّهُ لاَ يُفْلِحُ الظَّـلِمُونَ
(Verily, the wrongdoers shall never be successful.) Surely, both of these people will never acquire success, whoever falsely claims that Allah sent him and whoever refuses Allah's Ayat.
Maududi - Sayyid Abul Ala Maududi - Tafhim al-Qur'an
That is. "Allah is a witness that I have been appointed a Messenger by Him and whatever I say is from Him."
Mere guess-work or speculation does not suffice for testifying to anything: none can testify to a thing with certainty without the necessary knowledge about it. The question implies: "Do you really have the knowledge that there is any other Sovereign with authority than Allah, Who is worthy of service and worship?"
That is, "You may, if you so like, give false testimony without any knowledge, but, as for me, I cannot give such a testimony."
It means that those, who possess the knowledge of revealed Books, know it for certain that there is only One God, Who has no partner in His Godhead. Therefore they can discern the right creed about Allah from among many different kinds of other creeds' and theories about Godhead, just as any person can identify his own child from among many thousands of other children.
"False allegation" is the claim that there are many other partners with Allah in His Godhead who have divine attributes and powers and are thus worthy of worship. It is also false to allege that Allah Himself has made such and such His special courtiers and has enjoined (or at least approved) that Divine attributes should be ascribed to them and that they should be treated with reverence, like Allah.
"Allah's Signs" are all those signs that point to the fact that there is only One God in the universe and that all others are His servants. These signs are spread all over the universe. They are found in the person of man himself and in the character and the great achievements of the Prophets and in the revealed Books. That is why the one, who, in the presence of all these "Signs," ascribes Divine attributes to others and considers them worthy of Divine rights, is in fact guilty of gross iniquity. It is indeed a great injustice that one should ascribe such Divine attributes to others without any evidence, knowledge, observation and experience merely on the basis of guess-work or the traditions of the forefathers. As a result of this false creed, he does injustice to Truth, to Reality, to his own self and to everything and everyone he deals with in this universe.
((O Muhammad): What thing is of most weight in testimony?) [6:19]. Said al-Kalbi: “The chiefs of Mecca said: ‘O Muhammad, we see that no one believes in what you say concerning the matter of messengership. We have asked the Jews and Christians about you and they claim that there is no description or mention of you in their Scriptures. So show us someone who will testify that you are a messenger, as you claim’. As a response, Allah, exalted is He, revealed this verse”.