The Quran states that "Allah loves those who maintain purity," and "He loves those who keep themselves pure and clean." While this can mean moral purity, it also is applied to physical cleanliness. This is particularly important during religious rituals. For instance, before a Muslim prays, he must undergo wudu, or ritual washing. One must also be clean when entering a mosque, and shoes are forbidden inside the prayer hall. Skalldyr points to this in a LEGO illustration of a scene from Tintin. In this scene, Thomson and Thomson were pursuing someone who ran into a mosque, but they did not stop to remove their shoes. The German sign translates roughly (thanks to Google Translate) as "Mosque - Visitors are asked to take off your shoes."