Mutarrif bin Mazin narrates with his chain, though I do not remember it, that Sayyiduna Ibn al-Zubayr (may Allah be pleased with him) said: Take the oath on the Qur'an.
Imam al-Shafi'i (may Allah have mercy on him) said: I saw Mutarrif in San'a taking oaths on the Qur'an, and the governors of the regions also used to administer oaths on the Qur'an, and in my view that is good.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الشهادات / 20704