The Prophet said: "Three days." I think he said, "And three nights during which the traveler may wipe over his leather socks." (Using translation from Ibn Mājah 554)

عَنِ النَّبِيِّ ﷺ أَنَّهُ قَالَ فِي الْمَسْحِ عَلَى الْخُفَّيْنِ «لِلْمُسَافِرِ ثَلَاثَةُ أَيَّامٍ وَلَيَالِيهِنَّ»