Sketch by Frithjof Schuon of a Muslim man. Found on p. 180 of IPMB
Christentum – Islam: Ausblicke auf eine esoterisch Ökumene (e-Book)
In this work, Frithjof Schuon compares Christianity and Islam and also looks at confessions within these world religions: Protestantism, Orthodoxy, and Shiism.