Sayyidina lbn Abbas (RA) reported that a delegation of the tribe of Abd Qays came to Allah’s Messenger (SAW). They said “O Messenger of Allah (SAW) , the tribe Rabi’ah lie in our path. So, we cannot come to you except during the sacred months. Do command us, therefore, things as we may abide by and invite those who are behind us.’ He said, “I command you four things: faith in Allah”, and he explained it to them as, “testimony that there is no God but Allah and I am Allah’s Messenger, observing the Salah and paying the Zakah, and to pay one-fifth of what you gain as booty.”
[Ahmed 2120, Bukhari 53, Muslim 17, Abu Dawud 3692,Nisai 5041]