Sahih Bukhari Volume 9, Book 93, Hadith 7197

وَقَالَ خَارِجَةُ بْنُ زَيْدِ بْنِ ثَابِتٍ عَنْ زَيْدِ بْنِ ثَابِتٍ، أَنَّ النَّبِيَّ صلى الله عليه وسلم أَمَرَهُ أَنْ يَتَعَلَّمَ كِتَابَ الْيَهُودِ، حَتَّى كَتَبْتُ لِلنَّبِيِّ صلى الله عليه وسلم كُتُبَهُ، وَأَقْرَأْتُهُ كُتُبَهُمْ إِذَا كَتَبُوا إِلَيْهِ، وَقَالَ عُمَرُ وَعِنْدَهُ عَلِيٌّ وَعَبْدُ الرَّحْمَنِ وَعُثْمَانُ مَاذَا تَقُولُ هَذِهِ قَالَ عَبْدُ الرَّحْمَنِ بْنُ حَاطِبٍ فَقُلْتُ تُخْبِرُكَ بِصَاحِبِهِمَا الَّذِي صَنَعَ بِهِمَا‏.‏ وَقَالَ أَبُو جَمْرَةَ كُنْتُ أُتَرْجِمُ بَيْنَ ابْنِ عَبَّاسٍ وَبَيْنَ النَّاسِ‏.‏ وَقَالَ بَعْضُ النَّاسِ لاَ بُدَّ لِلْحَاكِمِ مِنْ مُتَرْجِمَيْنِ‏

Kharija bin Zaid bin Thabit said that Zaid bin Thabit said, “The Prophet (pbuh) ordered me to learn the writing of the Jews. I even wrote letters for the Prophet (pbuh) (to the Jews) and also read their letters when they wrote to him.” And Umar said in the presence of Ali, Abdur –Rahman and Uthman, “What is this woman saying?” Abdur –Rahman bin Hatib said, “She is informing you about her companion who has committed illegal sexual intercourse with her.” Abu Jamra said, “I was an interpreter between Ibn Abbas and the people”. Some people said, “A ruler should have two interpreters.”