The truce of Hudaibiya turned out to be a complete triumph for Islaam. The numbers of Muslims increased by leaps and bounds. Rasulullah thought that it was the opportune moment to spread the 'Message of Allah' far and wide, including the Kings around Arabia. Rasulullah addressed his companions as followers: 'Now the time has arrived that you should spread the Message of Truth'. Rasulullah selected some intelligent Sahaba, and entrusted them with written invitations to Arab rulers and neighboring Kings. He sent envoys to the Emperor of Rome, the Qaysar of Persia, the Aziz of Egypt, the Negus of Abyssinia and the Arab chiefs, inviting them to embrace Islaam.
Hazrat Abdullah bin Huzaifa (R.A.) took a letter of invitation to the Persian Court. The Qaysar was enraged and tore the letter into pieces. Rasulullah suprised the Sahaba by telling them that the Qaysar was dead. The Qaysar's son had assassinated him that night .
Rasulullah also sent a letter to the Arab Chiefs inviting them to worship one 'ALLAH. The epistles that were sent to the various kings in the year 7 A.H. show that Rasulullah was an Apostle of Allah for the whole of mankind and he, though surrounded with an unstable situation, believed that Islaam would prevail and its light would illuminate the world.
Contents of the biography of the Prophet Muhammed