Abbas - Tanwîr al-Miqbâs min Tafsîr Ibn ‘Abbâs
Then He taught the believers the path of divine Oneness so that the Jews and Christians had an indication of what this divine Oneness means, saying: (Say (O Muslims): We believe in Allah and that which is revealed unto us) i.e. in Muhammad and the Qur'an (and that which was revealed unto Abraham) i.e. we believe in Abraham and his Scripture, (and Ishmael) and we believe in Ishmael and his Scripture, (and Isaac) and in Isaac and his Scripture, (and Jacob) and in Jacob and his Scripture, (and the tribes) and in the sons of Jacob and their Scriptures, (and that which Moses and Jesus received) i.e. we believe in Moses and the Torah and in Jesus and the Gospel, (and that which the Prophets received) we also believe in all the prophets and their Scriptures (from their Lord. We make no distinction between any of them) that Allah sent them as prophets to teach divine Oneness, (and unto Him we have surrendered) we acknowledge that we worship Him and declare that there is only one true God.
Say: (this address is to the believers) ‘We believe in God, and in that which has been revealed to us, the Qur’ān, and revealed to Abraham, the ten scrolls, Ishmael, Isaac, Jacob, and the Tribes, his sons, and that which was given to Moses, the Torah, and Jesus, the Gospel, and the prophets, from their Lord, of Books and signs, we make no division between any of them, believing in some and disbelieving in others in the manner of Jews and Christians, and to Him we submit’.
Say: 'We believe in God, to the end of this [statement: and in that which has been revealed to us, and revealed to Abraham, Ishmael, Isaac, Jacob, and the Tribes, and that which was given to Moses, and Jesus, and the prophets, from their Lord]
We make no division between any of them, by denying the religion of some of them or deeming false their creed, while affirming that of others and their truthfulness; nay, we believe that they have all coverged upon the truth and agreed about the Oneness of God; we accept all of these religions on the basis of the [belief in the] Oneness that comprehends all of them; [and to Him we submit'.]
The Muslim believes in all that Allah `revealed and all the Prophets
Allah directed His believing servants to believe in what He sent down to them through His Messenger Muhammad and in what was revealed to the previous Prophets in general. Some Prophets Allah mentioned by name, while He did not mention the names of many others. Allah directed the believers to refrain from differentiating between the Prophets and to believe in them all. They should avoid imitating whomever Allah described as,
(And wish to make distinction between Allah and His Messengers (by believing in Allah and disbelieving in His Messengers) saying, "We believe in some but reject others,'' and wish to adopt a way in between. They are in truth disbelievers) (4:150-151).
Al-Bukhari narrated that Abu Hurayrah said, "The People of the Book used to read the Torah in Hebrew and translate it into Arabic for the Muslims. The Messenger of Allah said,
(We believe in Allah, and bear witness that we are Muslims (i.e. we submit to Allah)) (3:52) during the two (voluntary) Rak`at before Fajr.''
Abu Al-`Aliyah, Ar-Rabi` and Qatadah said, "Al-Asbat are the twelve sons of Jacob, and each one of them had an Ummah of people from his descendants. This is why they were called Al-Asbat.'' Al-Khalil bin Ahmad and others said, "Al-Asbat among the Children of Israel are just like the tribes among the Children of Isma`il.'' This means that the Asbat are the various tribes of the Children of Israel, among whom Allah sent several Prophets. Moses said to the Children of Israel,
(Remember the favor of Allah to you: when He made Prophets among you, made you kings) (5:20). Also, Allah said,
وَقَطَّعْنَـهُمُ اثْنَتَىْ عَشْرَةَ أَسْبَاطًا
(And We divided them into twelve tribes) (7:160).
Al-Qurtubi said, "Sibt is the group of people or a tribe all belonging to the same ancestors.''
Qatadah said, "Allah commanded the believers to believe in Him and in all His Books and Messengers. '' Also, Sulayman bin Habib said, "We were commanded to believe in the (original) Torah and Injil, but not to implement them.''
Maududi - Sayyid Abul Ala Maududi - Tafhim al-Qur'an
In order to understand the true significance of this answer, two things should be kept in mind.
(1) Judaism and Christianity were born long after the death of Abraham. Judaism, with its special rituals, peculiar regulations, etc., took its birth and name some tour hundred years before Christ. As to "Christianity", it took its name and adopted its special creed and form long after the recall of Jesus. Thus it is clear that their claim that one must become a Jew or a Christian in order to obtain guidance was historically untenable. For in that case, Abraham, Jesus and all the other Prophets and all the good people who had passed away long before the birth of Judaism and Christianity could not be counted among the right-guided persons for the simple reason that these "religions" did not exist at the time they lived. Thus, it was obvious that the Jews and Christians could not say that these Prophets were not right-guided, nor could they claim that they followed Judaism or Christianity. As a corollary to this, true Guidance did not, even according to them, consist of the particular features which divided them into two distinct religions, but it was that eternal universal way which has been shown by all the Messengers of Allah and which has always been followed by the good people of all ages.
(2) It also meant to warn the Jews and the Christians that both practised shirk and had, therefore, swerved from the way of Abraham, who did not associate any other object with Allah in his worship, his reverence, his submission and his obedience to Him. They could not deny this because their own Scriptures bore testimony to it.
"We do not discriminate against any of them" means that we believe in all the Prophets of Allah and reject none. It is obvious that all the Prophets who came from Allah brought the same Truth and invited the people to the same Guidance and Right Way. Hence anyone who follows the Truth must accept all the Prophets. Those who accept one Prophet and reject the other really reject even the one whom they profess to accept. Had they followed the universal Guidance taught by Moses, Jesus and other Prophets, they could not have rejected any other Prophet (i.e. Muhammad, Allah's peace be upon him). As a matter of fact, they were not following the teachings of any Prophet, but merely professing to accept their own Prophets just because their fathers did so. Thus their real religion was prejudice, race-worship and blind imitation of their forefathers.
Say: “We believe in God and in that which has been revealed to us and revealed to Abraham Ishmael Isaac Jacob and the tribes and that which was given to Moses and Jesus and the prophets from their Lord we make no division between any of them and to Him we submit.” Because our Prophet ﷺ believed in everything that was revealed before him he was honored with everything that [God] had conferred in honor to [the prophets] before him. When [God] proclaimed the harmony muwāfaqa of all [the messages of the prophets] He entrusted everything in existence [to fall] under [Muḥammad's] banner. [Muḥammad] said “Adam and all others shall be under my banner on the Day of the Resurrection.” When his community believed in everything that God revealed to His messengers and made no division between any of them they drew the highest share in honor and took precedence over all communities.