Musannaf Ibn Abi Shayba 13:2445

Abu Bakr narrated to us, he said: Waki' narrated to us, he said: Al-Rabi' ibn Muslim narrated to us, from Harun Abu Uthman al-'Ijli, he said: Abdullah ibn Mas'ud said: If procrastination (al-ma'k) were a man, he would be an evil man. And procrastination is a form of injustice.