Sayyiduna Abu Kanaf (may Allah be pleased with him) narrates that I was walking with Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) in the slave market when he heard a man swearing an oath by a surah of the Qur'an. Then Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) said: "For every verse of it, an oath is required."