In 2006 the Moro Islamic Liberation Front (MILF) produced rules of engagement in hostilities for members of its armed wing, the Bangsamoro Islamic Armed Forces, which reference Islamic law and are also compliant with international humanitarian law (IHL). The release of these rules came following engagement with the MILF by both national and international humanitarian organizations. This article examines the role of Islamic scholars in the MILF and how they contributed to the development of the rules of engagement and the dissemination of humanitarian principles and IHL to its fighters. It also examines the support that humanitarian organizations provided to MILF’s Islamic scholars in their work on IHL. The findings show that MILF’s religious scholars played a major role in promoting IHL to the group’s armed wing through a framing of IHL from an Islamic perspective. A major motivation for the MILF to engage its Islamic scholars on IHL was the desire for international legitimacy as it was involved in a peace process with the government of the Philippines.