Narrated Zayd ibn Thabit (may Allah swt please with him):
The Apostle of Allah (peace and blessings of Allah swt be upon him) ordered me (to learn the writing of the Jews), so I learnt for him the writing of the Jews. He (peace and blessings of Allah swt be upon him) said: "I swear by Allah, I do not trust Jews in respect of writing for me." So I learnt it, and only a fortnight passed that, I mastered it. I would write for him when he wrote (to them), and read to him when something was written to him.