Sayyiduna Abu Umamah (may Allah be pleased with him) said that the Prophet (peace and blessings be upon him) said: "I have been given preference through four things: the earth has been made a mosque and a means of purification for me. If any man of my Ummah comes to pray and finds nothing to pray on, he will find the earth a mosque and a means of purification. I have been sent to all people. I have been helped by awe from a distance of two months' journey, and the spoils of war have been made lawful for me."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 4267