Imam Bukhari narrates: Isma'il narrated to us, he said: Imam Malik bin Anas narrated to us, from his uncle Abu Suhail bin Malik, from his father, that he heard Hazrat Talhah bin Ubaidullah say that

a man from the people of Najd came to the Messenger of Allāh ﷺ; the hair of his head was disheveled; we heard the humming sound of his voice but did not understand what he was saying, until he came near, and he was asking about Islam. So the Messenger of Allāh ﷺ said: There are five prayers in a day and a night. He said: Are there any others besides these? He said: No! Unless you pray voluntary (Nafl) prayers. The Messenger of Allāh ﷺ said: And fasting Ramadan. He said: Are there any other fasts obligatory upon me besides these? He said: No! Unless you fast voluntarily. Hazrat Talhah said: And the Messenger of Allāh ﷺ mentioned Zakah to him. He said: Is anything else obligatory upon me to give besides Zakah? He said: No! Unless you give voluntary charity. That man turned away, saying: By Allāh! I will neither add to nor reduce from these obligations. The Messenger of Allāh ﷺ said