Kiai is a charismatic figure who has influence for the existence of pesantren. Spiritualleadership is a typology of kiai based on the values of Islamic spirituality. This studyexamines the source of authority of the spiritual leadership of the kiai using perspectiveof Weber's authority theory. Using the approach of religious phenomenology, this studyobserves phenomenologically the spiritual leadership of kiai at Pesantren al-Fatah (orknown as Pesantren Temboro), which became the center of the biggest ideology ofJamaah Tabligh in Southeast Asia. Research data was obtained through in-depthinterviews, active participation, documentation, and open questionnaires. This researchfound the three authorities of spiritual leadership at Pesantren Temboro, namelytraditional, charismatic, and rational. First, traditional authority derives from threetraditions: (1) pesantren education, (2) Jamaah Tabligh, and (3) the NaqsyabandiyahKhalidiyahcongregation. Second, charismatic authority derives from the spiritualqualities of the kiai and is reinforced by karomah. Third, rational authority derives fromthe rational efforts of kiai in opening formal madrasah as a form of modernization inIslamic educational institutions.