Source text
أَنْ يَمْسَحَ بِالْحَجَرِ الْأَوَّلِ مِنْ جِهَةِ الْمُقَدَّمِ إِلَى خَلْفٍ، وَبِالثَّانِي مِنْ خَلْفٍ إِلَى قُدَّامٍ، وَبِالثَّالِثِ مِنْ قُدَّامٍ إِلَى خَلْفٍ إِذَا كَانَتِ الْخُصْيَةُ مُدَلَّاةً
• Where the stated physical condition applies, the sequence given is: front-to-back, back-to-front, then front-to-back.
• If that condition does not apply, the text says to begin from back to front.
• The purpose is effective cleaning while avoiding spreading impurity.