Abbas - Tanwîr al-Miqbâs min Tafsîr Ibn ‘Abbâs
(Perfected is the Word of thy Lord) the Qur'an, detailing the commands and prohibitions (in truth) in His speech (and justice) from Him. (There is naught that can change His words) the Qur'an; it is also said that this means: the Word of your Lord has prescribed that His friends shall triumph. He is truthful in His speech and just in that which shall come. Nothing can change His words about His giving help to His friend. It is also said that this means: the religion of your Lord is now manifest, people truthfully believe that it is Allah's religion. Allah's command is just and nothing will ever change His religion. (He is the Hearer) of their speech, (the Knower) of them and their works.
Perfected is the word of your Lord, in the way of rulings and appointed terms, in truthfulness and justice (sidqan wa-‘adlan is for specification); none can change His words, either by contravening [His rulings] or evading [His appointed terms]. He is the Hearing, of what is said, the Knowing, of what is done.
Perfected is the word of your Lord in truthfulness and justice, that is, His decree has been completed in pre-eternity, in the sense of what He has decreed and determined of the submission of those who will submit and the disbelief of those who will disbelieve, the love of those whom He will love and the enmity of those to whom He will be an enemy, a decree concluded and a judgement that is truthful and corresponding to what will happen, equitable in the correspondence of every speech, every perfection and state to the preparedness of that person from whom they will issue and their being entailed in him; none can change, His pre-eternal judgements. He is the Hearer, of the predetermined words and acts which they manifest, the Knower, of what they hide.
(So if you are in doubt concerning that which We have revealed unto you, then ask those who are reading the Book before you. Verily, the truth has come to you from your Lord. So be not of those who doubt (it).) 10:94 The conditional `if' in this Ayah does not mean that `doubt' will ever occur to the Prophet. Allah said,
وَتَمَّتْ كَلِمَةُ رَبِّكَ صِدْقاً وَعَدْلاً
(And the Word of your Lord has been fulfilled in truth and in justice.) Qatadah commented, "In truth concerning what He stated and in justice concerning what He decided.'' Surely, whatever Allah says is the truth and He is Most Just in what He commands. All of Allah's statements are true, there is no doubt or cause for speculation about this fact, and all His commandments are pure justice, besides which there is no justice. All that He forbade is evil, for He only forbids what brings about evil consequences. Allah said in another Ayah,
(He commands them with good; and forbids them from evil...) 7:157 until the end of the Ayah.
لاَ مُبَدِّلَ لِكَلِمَـتِهِ
(None can change His Words.) meaning, none can avert Allah's judgment whether in this life or the Hereafter,
(And He is the All-Hearer,) Hearing, His servants' statements,
(The All-Knower.) of their activities and lack of activity, Who awards each according to their deeds.
Maududi - Sayyid Abul Ala Maududi - Tafhim al-Qur'an
The `speaker' in this sentence is the Holy Prophet and the addressees are his followers, who desired that a Sign should be shown for the conversion of the disbelievers. They have been told that no Sign will be shown, for Allah had made all the realities plain in the Qur'an. As regards their conflict with falsehood, He has decreed that the followers of the Truth will have to exert for its domination in the natural way without expecting any supernatural intervention from Him. The Holy Prophet has, therefore, been asked to declare, "Should I, then, seek some authority higher than Allah to revise His decree and to send down such a miracle as should force them to believe?" (Please refer also to E.N. 76).
That is, "These principles, that have been laid down for the domination of the Truth, are not new ones which might have been invented today to explain away the difficulties and obstacles of the Way. All those people, who possess the knowledge of the Divine Books and are acquainted with the Mission of the Prophets, will bear testimony that whatever is being stated in the Qur'an is the very Truth, which is eternal and has never changed. "