Sayyiduna Mu'awiyah bin Haydah (may Allah be pleased with him) said: I came to the Messenger of Allah (peace and blessings be upon him) and said: "O Messenger of Allah, I did not come to you until I had sworn, as many times as the number of these fingers of mine, that I would not come to you. So by the One who sent you with the truth, with what has Allah sent you?" He (peace and blessings be upon him) said: "With Islam." I said: "What is Islam?" He (peace and blessings be upon him) said: "That you surrender your heart to Allah, turn your face towards Allah, perform the obligatory prayer and pay the obligatory zakah. (Muslims are to one another) two brothers and helpers. Allah does not accept the repentance of a servant who commits shirk after his Islam."
And I heard the Messenger of Allah (peace and blessings be upon him) say: "You will be gathered here" and he (peace and blessings be upon him) pointed with his hand towards Syria (al-Sham) "on foot, riding, and on your faces. You will be presented before Allah with your mouths sealed, and the first thing to testify about each of you will be his thigh."
And I heard the Messenger of Allah (peace and blessings be upon him) say: "You complete the number of seventy nations; you are the last of them and the most honoured of them before Allah."
Hadith Referenceالمعجم الكبير للطبراني / باب الميم / 17085