Musannaf Ibn Abi Shayba 17:1120

Ibn Mahdi narrated to us, from Sufyan, from Sa’d ibn Ibrahim, from ‘Ata’ ibn Yasar, who said: The Jews used to come to the Muslims and speak to them, and they (the Muslims) would find it good—or he said: they would like it. They mentioned that to the Messenger of Allah, may Allah bless him and grant him peace, and he said: "Do not believe them and do not disbelieve them, and say: 'We believe in Allah and what has been revealed to us' (to the end of the verse)."