Zayd bin Aslam زيد بن أسلم · The Book Of Faith and its Signs

The Prophet ; and when he would hate to go back to disbelief as much as he would hate to be thrown into the fire."

A man said to him: "Why don't you go out and fight?" He said: "I heard the Messenger of Allah say: 'Islam is built on five (pillars): Testimony that there is none worthy of worship except Allah, establishing Salah, giving Zakah, Hajj, and fasting Ramadan.'"