حدثنا محمد بن علي، قال سمعت أبي يقول: قال عبد الله ابن المبارك: إذا ابتليت بالقضاء فعليك بالأثر.
Abdullah bin Mubarak said:
"If one becomes a judge or arbitrator, then they should always follow that which has been narrated."
Reference: Sunnah.com : Book 56, Hadith 9
English : Book 55, Hadith 396
Arabic : Book 56, Hadith 414