The Quran

153

يَسأَلُكَ أَهلُ الكِتابِ أَن تُنَزِّلَ عَلَيهِم كِتابًا مِنَ السَّماءِ ۚ فَقَد سَأَلوا موسىٰ أَكبَرَ مِن ذٰلِكَ فَقالوا أَرِنَا اللَّهَ جَهرَةً فَأَخَذَتهُمُ الصّاعِقَةُ بِظُلمِهِم ۚ ثُمَّ اتَّخَذُوا العِجلَ مِن بَعدِ ما جاءَتهُمُ البَيِّناتُ فَعَفَونا عَن ذٰلِكَ ۚ وَآتَينا موسىٰ سُلطانًا مُبينًا

Muhammad Asad

THE FOLLOWERS of the Old Testament¹ demand of thee [O Prophet] that thou cause a revelation to be sent down to them from heaven.² And an even greater thing than this did they demand of Moses when they said, "Make us see God face to face" - whereupon the thunderbolt of punishment overtook them for this their wickedness.³ After that, they took to worshipping the [golden] calf - and this after all evidence of the truth had come unto them! None the less, We effaced this [sin of theirs], and vouchsafed unto Moses a clear proof [of the truth],

As is evident from the sequence, the term ahl al-kitab ("followers of earlier revelation") refers here specifically to the Jews, which justifies its rendering as "followers of the Old Testament".
Sc., "in proof of thy prophethood". Alternatively, the sentence may be understood thus: "They ask thee to bring down unto them an [actual] book from heaven." In view, however, of the oft-repeated Qur'anic statement that the Jews were convinced that they alone could be granted divine revelation, it seems to me that the rendering adopted by me is the more appropriate.
See 2:55 and the corresponding note.