“Muhammad Rasul Allah,” meaning literally: “Muhammad is the messenger of Allah.” This is the inscription on the original seal that was used by the Prophet, may Allah bless him and give him peace, to sign the letters he sent to various rulers.
Here is a hadith about the seal:
Anas Ibn Malik said: “Rasulullah (pbuh) had a ring made of silver and its (inlaid) gem was also of silver. When the Prophet (pbuh) wanted to write to the leaders of foreign states, he ordered a seal-ring to be made. Rasullullah (saas) therefore had a ring made, the whiteness of which is still before my eyes. The inscription engraved on the ring of Rasulullah (pbuh) was ‘Muhammad Rasulullah,’ of which in the first line was engraved ‘Muhammad,’ in the second line ‘Rasul,’ and in the third line ‘Allah’.”
The Prophet, may the peace and blessings of Allah be upon him, was illiterate, so he had the ring made as his signature seal. And indeed, The Prophet (saw) had the ring cast in silver, but being so filled with love and reverence for Allah almighty, did not want to place his name above the name of Allah. Contrary to the normal way of reading from top to bottom, he had the inscription written upwards, “Muhammed Rasul Allah” as can be seen in the photo above.
The original ring, however, was lost down the well of Aris during the reign of hadhrat Uthmaan. The Seal that is in the Topkapi palace was made thereafter, and is not an exact replica of the orignal, which was never recovered, according to this hadith.
that when Abu Bakr became the Caliph, he wrote a letter to him (and stamped it with the Prophet’s ring) and the engraving of the ring was in three lines: Muhammad in one line, ‘Apostle’ in another line, and ‘Allah’ in a third line. Anas added: ‘the ring of the Prophet was in his hand, and after him, in Abu Bakr’s hand, and then in ‘Umar’s hand after Abu Bakr. When Uthman was the Caliph, once he was sitting at the well of Aris. He removed the ring from his hand and while he was trifling with it, dropped into the well. We kept on going to the well with Uthman for three days looking for the ring, and finally the well was drained, but the ring was not found. – Bukhari, Volume 7, Book 72, Number 767.