جامع الترمذي

Narrated Zaid bin Thabit: "The Messenger of Allah (ﷺ) ordered me to learn some statements from writings of the Jews for him, and he said: 'For indeed by Allah! I do no trust the Jews with my letters.'" He said: "Half a month did not pass before I learned it, when he (ﷺ) wanted to write to the Jews I would write it to them, and when they wrote to him I would read their letters to him."