Sayyiduna Abu Umamah (may Allah be pleased with him) said that a man said: "O Messenger of Allah! Permit me to roam the land (siyahah)." He (peace and blessings be upon him) said: "The roaming (siyahah) of my ummah is in jihad in the path of Allah."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب السير / 18506