Sahih Bukhari Volume 002, Book 026, Hadith Number 795.
Narated By 'Ikrima : Ibn Abbas said: "Allah's Apostle delivered a sermon on the Day of Nahr, and said, 'O people! (Tell me) what is the day today?' The people replied, 'It is the forbidden (sacred) day.' He asked again, 'What town is this?' They replied, 'It is the forbidden (Sacred) town.' He asked, 'Which month is this?' They replied, 'It is the forbidden (Sacred) month.' He said, 'No doubt! Your blood, your properties, and your honor are sacred to one another like the sanctity of this day of yours, in this (sacred) town (Mecca) of yours, in this month of yours.' The Prophet repeated his statement again and again. After that he raised his head and said, 'O Allah! Haven't conveyed (Your Message) to them'. Haven't I conveyed Your Message to them?' " Ibn Abbas added, "By Him in Whose Hand my soul is, the following was his will (Prophet's will) to his followers: It is incumbent upon those who are present to convey this information to those who are absent Beware don't renegade (as) disbelievers (turn into infidels) after me, Striking the necks (cutting the throats) of one another.'"