Narrated Abu Hurairah (Radi Allahu anhu): the prophet (Sallallahu alaihi wasallam) said, "Whoever believes in Allah and His messenger;performs salat,observes fast during the month of Ramadan,then it will be a promise binding upon Allah to admit him to paradise, no matter whether he fights in Allah's cause or remains in the land where he is born." In another hadith it is mentioned: in order to enter paradise one must believe in the six articles of faith. And must act on the five principles of Islam. The people said, "Paradise hadls one hundred grades which Allah has reserved for the Mujahidun who fight in His cause,and the distance between each of two grades is like that of the distance between heaven and earth. So, when you ask Allah for Jannah, ask for  Al-Firdaus which is the middle and highest part of paradise." [The subnarrator added, "I think the prophet (Sallallahu alaihi wasallam) also said, 'Above it I.e Al-Firdaus) is the Throne of Allah the Most Gracious, and from it gush forth the rivers of paradise]."
(Sahih Al-Bukhari,vol.4,Hadith No.48).