Musannaf Ibn Abi Shayba 28:17

'Abd al-Rahim ibn Sulayman narrated to us, from Mujalid, from Masruq, from 'Abdullah ibn Mas'ud, who said: "There is no judge who judges between people but he will be gathered on the Day of Resurrection, and an angel will be holding him by the back of his neck until he stands with him at the edge of Hell. Then he will raise his head toward the Most Merciful; if He says, 'Cast him,' he will cast him into a fall of forty autumns." He said: And Masruq said, "For me to judge for one day with justice and truth is more beloved to me than a year in which I fight in the way of Allah."