It is narrated from Sayyiduna Khuzaymah bin Thabit (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) set three (days) for us, and had we asked for more (time), he (peace and blessings be upon him) would have given us more; meaning for the traveller's wiping over leather socks.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الطهارة / 1319