Sahl bin Mu'adh bin Anas al-Juhani narrates from his father, Sayyiduna Mu'adh bin Anas (may Allah be pleased with him), that the Messenger of Allah (peace and blessings be upon him) said: "The reward of prayer, fasting and remembrance (of Allah) is multiplied up to seven hundred times over that of spending in the path of Allah."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب السير / 18574