وَإِذَا قِيلَ لَهُمْ ءَامِنُوا۟ بِمَآ أَنزَلَ ٱللَّهُ قَالُوا۟ نُؤْمِنُ بِمَآ أُنزِلَ عَلَيْنَا وَيَكْفُرُونَ بِمَا وَرَآءَهُۥ وَهُوَ ٱلْحَقُّ مُصَدِّقًۭا لِّمَا مَعَهُمْ ۗ قُلْ فَلِمَ تَقْتُلُونَ أَنۢبِيَآءَ ٱللَّهِ مِن قَبْلُ إِن كُنتُم مُّؤْمِنِينَ
And when it is said to them, "Believe in what Allah has revealed," they say, "We believe [only] in what was revealed to us." And they disbelieve in what came after it, while it is the truth confirming that which is with them. Say, "Then why did you kill the prophets of Allah before, if you are [indeed] believers?"
When this group of Jews was told to have faith in the truth and guidance that Allah revealed to His Prophet, they said that they believed in what had been revealed to their prophets, and denied anything besides this, and in what was revealed to Muhammad (peace be upon him), although the Qur’ān is the truth, confirming what Allah had already revealed to them. Had they truly believed in what had been revealed to them, they would have believed in the Qur’ān. So, ask them then, O Muhammad, why they killed the prophets of Allah before, if they really had faith in the truth they brought to them.