A man of the people of Najd with dishevelled hair came to God’s messenger. We could hear the sound of his voice, but could not understand what he was saying till he came near God’s messenger and we realised that he was asking about Islam. God’s messenger said, “Five times of prayer each day and night.” He asked, “Must I observe any more than them?” He replied, “No, unless you do it voluntarily.” God's messenger said, “And fasting during the month of Ramadan.” He asked, “Must I observe anything else?” He replied, “No, unless you do it voluntarily.” Talha said that God's messenger mentioned the zakat to him, and he asked, “Must I pay anything else?” He replied, “No, unless you do it voluntarily.” He said that the man turned away saying, “I swear by God that I shall not add anything to this or fall short of it.” So God’s messenger said, “The man will prosper if he is speaking the truth.” (Bukhari and Muslim.)