Narrated Talha bin 'Ubaid-Ullah (Radi-Allahu 'anhu):
A bedouin with unkempt hair came to Allah's Apostle (Sallallahu 'Alaihi WaSallam) and said, "O Allah's Apostle! Inform me what Allah has madecompulsory for me as regards the prayers." He replied: "You have to offerperfectly the five compulsory prayers in a day and night (24 hours), unlessyou want to pray Nawafil." The bedouin further asked, "Inform me what Allahhas made compulsory for me as regards fasting." He replied, "You have tofast during the whole month of Ramadan, unless you want to fast more asNawafil." The bedouin further asked, "Tell me how much Zakat Allah hasenjoined on me." Thus, Allah's Apostle (Sallallahu 'Alaihi Wa Sallam)
informed him about all the rules (i.e. fundamentals) of Islam. The bedouinthen said, "By Him Who has honored you, I will neither perform any Nawafilnor will I decrease what Allah has enjoined on me. Allah's Apostle
(Sallallahu 'Alaihi Wa Sallam) said, "If he is saying the truth, he willsucceed (or he will be granted Paradise)."
Bukhari Vol. 3 : No. 115