The Quran

قُل يا أَهلَ الكِتابِ لِمَ تَصُدّونَ عَن سَبيلِ اللَّهِ مَن آمَنَ تَبغونَها عِوَجًا وَأَنتُم شُهَداءُ ۗ وَمَا اللَّهُ بِغافِلٍ عَمّا تَعمَلونَ

Muhammad Asad

Say: "O followers of earlier revelation! Why do you [endeavour to] bar those who have come to believe [in this divine writ] from the path of God by trying to make it appear crooked, when you yourselves bear witness¹ [to its being straight]? For, God is not unaware of what you do."

I.e., "through your own scriptures" (see note 69 above, as well as note 33 on 2:42). This is an allusion to the attempts of Jews and Christians to "prove" that Muhammad had "borrowed" the main ideas of the Qur'an from the Bible and twisted them out of context so as to suit his own alleged "ambitions".