Sayyiduna Abu Umamah al-Bahili (may Allah be pleased with him) narrates from Sayyiduna Mu'adh bin Jabal (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "The head of this matter is Islam, and whoever accepts Islam is safe; its pillar is prayer, and the peak of its hump is jihad, and none attains it except the best of them."
Hadith Referenceالمعجم الكبير للطبراني / باب الميم / 17232