Sahih Bukhari
Prophets
Volume: 004 / Book Number: 055 / Hadith Number: 658
Narrated Abu Huraira:
Allah's Apostle said "How will you be when the son of Mary (i.e. Jesus) descends amongst you and he will judge people by the Law of the Quran and not by the law of Gospel (Fateh-ul Bari page 304 and 305 Vol 7)