Imam Sadiq (a.s) asked Ali ibn Abdul-Aziz: “Do You want me to tell you the major, the minor and the highest principles of Islam?” He said: “Yes.” Imam Sadiq (a.s) said: “The major principle is prayer.” The minor principle is the payment of the alms tax. But the highest principle is holy war in the way of God. Do you want me to inform you about the gates of goodness? Fasting is similar to armor against the Fire of Hell. Charity will eliminate the sins. The same holds true for staying up late at night and praying to the Lord.” Then Imam Sadiq (a.s) recited the following verse: “Their limbs do forsake their beds of sleep, the while they call on their Lord, in fear and hope: and they spend (in charity) out of the sustenance which We have bestowed on them.” [The Holy Quran: Sajda 32:16]