1. Book of Purification
١۔ كِتَابٌ الطَّهَارَةِ
The Messenger of Allah ﷺ allowed three days and nights for the traveller and one day and night for one who is not travelling (i.e., with regard to wiping over the khuffain or leather slippers) (Using translation from Aḥmad 1126)
«جَعَلَ رَسُولُ اللَّهِ ﷺ ثَلَاثَةَ أَيَّامٍ وَلَيَالِيَهُنَّ لِلْمُسَافِرِ وَيَوْمًا وَلَيْلَةً لِلْمُقِيمِ» يَعْنِي الْمَسْحَ عَلَى الْخُفَّيْنِ