Postal day may not be old, but the exchange of letters began long ago. Many prophets and rulers down the ages sent letters far and near for various needs, using swift horsemen, pigeons and other birds to carry them.

Postal day brings to mind the letters sent by Prophet Muhammad (PBUH). Bearing the seal of prophethood, these letters reached the kings and emperors of the time. How beautifully he wrote them, for the good of humanity!

Many relics of those letters and invitations to kings and emperors still survive. He also sent a letter to the Roman emperor Heraclius. That historic letter bears the seal of the finality of prophethood and is still preserved in a museum in Jordan. It contains his remarkable words.

In the name of Allah, the Most Gracious, the Most Merciful.

From Muhammad, the servant and Messenger of Allah (PBUH), to Heraclius, the Emperor of Rome.

Peace be upon those who follow the right path. I invite you to Islam. If you want peace, accept Islam. If you accept Islam, Allah will give you a double reward. But if you refuse, the burden of the misguidance of all your subjects will fall on you.

O followers of the People of the Book! Set aside all disputed matters. We have reached agreement on a matter (tawhid, the oneness of Allah) on which there is no difference between you and us, and it is this:

"We will worship none but the one Allah. If you deny these things, then know that we will stand firm in all circumstances in our belief in the oneness of Allah."

Allah, Messenger, Muhammad (seal of prophethood)

Where the letter ends, the Prophet (PBUH) stamped his seal of prophethood.

Letters, and the postal system, are one of the main means of dawah, the call to Islam. The postal system was never wholly ineffective in any age; it has existed in every era. The Messenger of Allah (PBUH) did not stop at sending letters through envoys. To carry the call of tawhid, he travelled through many cities of Arabia, including the holy cities of Makkah and Madinah.

These letters of the Messenger of Allah (PBUH) are still preserved. Some are kept in a museum in Istanbul, and original copies of some are preserved in the Madinah museum in Saudi Arabia. The historic letter to the Roman emperor Heraclius is preserved in a museum in Jordan.

Those to whom he sent letters bearing the seal of prophethood, and envoys, with the invitation to Islam were:

• Heraclius, emperor of Rome, that is the Byzantine Empire.
• Musir ibn Sawa, king of Persia.
• Al-Muqawqis, ruler of Egypt.
• Ashama ibn Abjar, emperor of Ethiopia.
• He sent letters to Himyari Harith, prince of Yemen, and to Harith Ghasani.
• The Prophet also sent a letter to the governor of Sham.
• Khosrow Parvez, or Kisra Abruvez, the last great king of the Sasanian Empire, who reigned from 579 to 628. The Prophet (PBUH) sent him too a letter inviting him to Islam, which he tore up.

He then ordered Bazan, the ruler he had appointed in Yemen, to send two men to bring Muhammad (PBUH) from the Hijaz as a prisoner. Meanwhile, when the Prophet's envoy Abdullah (RA) returned and told him everything, the Prophet foretold the destruction of Khosrow Parvez. Khosrow Parvez was later put to death by his own son, Kavadh II.

This work of dawah by the Messenger of Allah (PBUH) was carried out on a large scale while he governed an independent state from Madinah. That was the best time for sending letters and delegations with the invitation to Islam, and it was an expression of the mission with which Allah sent him into the world. Allah says:

"It is He who has sent His Messenger with guidance and the religion of truth, to make it prevail over all religions, even though the polytheists dislike it." (Surah As-Saff)

Source: Jagonews24. First published in Bengali on The Agro News.