The notion of wilāya or walāya, friendship of man and God, lies at the heart of Islamic mysticism. The term designates a spiritual hierarchy of human beings, awliyāʾ, who attain an intimate relationship with God and as such play a special role in the maintenance, preservation and well-being of the world. According to this principle, the world cannot exist without the presence in it, at all times, of a fixed number of exemplary men, chosen by God to transmit, teach and perpetuate the sacred knowledge. The existence of the world, as well as its well-being, depend on the presence of these chosen ones known as awliyāʾ, abdāl, ṣiddīqūn and other appellations. Al-Ḥakīm al-Tirmidhī, in line with his binary outlook, distinguishes two types of awliyāʾ: those who are labelled ṣādiqūn (as well as awliyāʾ al-ḥaqq) – they are governed by ‘justice’ (ṣidq) and ‘law’ (ḥaqq); and those who are labelled ṣiddīqūn (as well as awliyāʾ Allāh). The ṣādiqūn relate to al-ḥaqq with its implications of power, law, justice and struggle; while the ṣiddīqūn, upon whom God’s mercy is bestowed, transcend struggle and effort and relish in the abundance of God’s nearness.