It is narrated from Sayyiduna Abu Ayyub al-Ansari (may Allah be pleased with him); he said: I heard the Messenger of Allah (peace and blessings be upon him) say: "Setting out in the path of Allah for one evening or one morning is better than everything upon which the sun rises and sets."
Hadith Referenceالمعجم الكبير للطبراني / باب الخاء / 4063