Isma'il bin Muslim narrates from al-Hasan (may Allah have mercy on him) concerning this saying of Allah: "And let no scribe or witness cause harm" [Surah al-Baqarah: 282]:
The scribe should not cause harm by writing something he was not instructed to write, nor should the witness cause harm by adding to his testimony.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الشهادات / 20606