From Sahih Bukhari (Hadith 7523):
Narrated 'Ubaidullah bin `Abdullah:`Abdullah bin `Abbas said, "O the group of Muslims! How can you ask the people of the Scriptures about anything while your Book which Allah has revealed to your Prophet contains the most recent news from Allah and is pure and not distorted? Allah has told you that the people of the Scriptures have changed some of Allah's Books and distorted it and wrote something with their own hands and said, 'This is from Allah, so as to have a minor gain for it. Won't the knowledge that has come to you stop you from asking them? No, by Allah, we have never seen a man from them asking you about that (the Book Al-Qur'an ) which has been revealed to you
Reference: Bukhari 7523