Humayd al-A'raj narrates from Mujahid (may Allah have mercy on him) that "Let no scribe or witness be harmed" [Surah al-Baqarah: 282] (means): when they are busy with their estate and their market.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الشهادات / 20605