Source text
وَالرَّابِعُ: مَشْكُوكٌ فِي طَهُورِيَّتِهِ، وَهُوَ سُؤْرُ الْبَغْلِ وَالْحِمَارِ، فَإِنْ لَمْ يَجِدْ غَيْرَهُ تَوَضَّأَ بِهِ وَتَيَمَّمَ، ثُمَّ صَلَّى
• The leftover of a donkey, and of the relevant mule, is not called impure. The doubt concerns whether it can remove ritual impurity.
• If no other water is available, the person performs Wudu with it and also Tayammum, then prays.