Allah directed His believing servants to believe in what He sent down to them through His Messenger Muhammad ﷺ 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,
وَيُرِيدُونَ أَن يُفَرِّقُواْ بَيْنَ اللَّهِ وَرُسُلِهِ وَيقُولُونَ نُؤْمِنُ بِبَعْضٍ وَنَكْفُرُ بِبَعْضٍ وَيُرِيدُونَ أَن يَتَّخِذُواْ بَيْنَ ذَلِكَ سَبِيلاًأُوْلَـئِكَ هُمُ الْكَـفِرُونَ حَقّاً
(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 ﷺ said,
«لَا تُصَدِّقُوا أَهْلَ الْكِتَابِ وَلَا تُكَذِّبُوهُمْ وقُولُوا: آمَنَّا بِاللهِ وَمَا أُنْزل إِلَيْنَا»
(Do not believe the People of the Book, nor reject what they say. Rather, say, `We believe in Allah and in what was sent down to us.)"
Also, Muslim, Abu Dawud and An-Nasa'i recorded that Ibn `Abbas said, "Mostly, the Messenger of Allah ﷺ used to recite,
ءَامَنَّا بِاللَّهِ وَمَآ أُنزِلَ إِلَيْنَا
(We believe in Allah and that which has been sent down to us) (2: 136), and,
ءَامَنَّا بِاللَّهِ وَاشْهَدْ بِأَنَّا مُسْلِمُونَ
(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,
اذْكُرُواْ نِعْمَةَ اللَّهِ عَلَيْكُمْ إِذْ جَعَلَ فِيكُمْ أَنْبِيَآءَ وَجَعَلَكُمْ مُّلُوكاً
(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."