Sufficiency of Qur'anic Signs

وَقَالُوا۟ لَوْلَا يَأْتِينَا بِـَٔايَةٍ مِّن رَّبِّهِۦٓ ۚ أَوَلَمْ تَأْتِهِم بَيِّنَةُ مَا فِى ٱلصُّحُفِ ٱلْأُولَىٰ

And they say, "Why does he not bring us a sign from his Lord?" Has there not come to them evidence of what was in the former scriptures?