Following is an excerpt from The Rays by Bediüzzaman Said Nursi (1878-1960), from The Risale-e-Nur collection:
The blessed phrases of the tashahhud were in fact a conversation between God Almighty and His Messenger on the night of the Messenger's Ascension (al-Mi'raj). What, then, is the reason for their inclusion in the canonical Prayer?THE ANSWER: The five daily Prayers are a sort of "ascension" for every believer who performs them. Therefore, the words to be uttered in the tashahhudmust be those spoken during the supreme Ascension of Muhammad, upon him be peace and blessings. Reciting them allows us to bring into mind this sacred conversation between God and His Messenger. Through this remembrance or recollection, the meanings of those blessed words gain universality and, as such, are no longer restricted to the intellectual or spiritual level of a believer. Their sacred, comprehensive meanings may thus be conceived, and through this conception their value and light are enhanced and expanded.For example, in order to greet Almighty God on that blessed night, the noblest Messenger, upon him be peace and blessings, said: at-Tahiyyatu li'llah. This means: "O my Lord! All the glorifications made by the living beings, and all the gifts they present to their Maker, through their lives are Yours alone. By visualizing them and though my belief, I too offer them to You."With the word at-tahiyyat, God's noblest Messenger, upon him be peace and blessings, was referring to all the worship that living creatures perform through their lives; he then offered this to God. Similarly, by the word al-mubarakat, which is the summation of at-tahiyyat, he meant the blessedness, abundance and worship of the creatures, and in particular those of seeds, grains, and eggs, which are the means of blessings and abundance and which cause one to exclaim: "How great are God's blessings!" And through the word as-salawat he visualized all the particular forms of worship performed by beings endowed with spirit and who are the summation of living beings, and offered them to the Divine Court with that comprehensive meaning. Finally, through the word at-tayyibat, he meant the luminous, elevated worship of perfected human beings and the angels closest in proximity to God, who are the summaries of the beings endowed with spirit; he offered this to the One he worshipped.On that night, God Almighty said: "Peace be upon you, O (most illustrious) Prophet!" This was an indirect command and an indication that in the future, hundreds of millions of people would say at least ten times a day: "Peace be upon you, O (most illustrious) Prophet!" This Divine greeting gave these words of salutation an extensive light and a most elevated meaning.The noblest Messenger, upon him be peace and blessings, responded to this greeting by saying: "Peace be upon us and upon all righteous servants of God!" This meant that the Messenger was hopefully and imploringly asking his Creator that in the future his vast Community and its righteous members would be favored with Islam in a way to represent Divine peace and blessings, and that those in his Community would greet one another with the words: "Peace be upon you!" "And upon you be peace!," which is a universal mark of Islam among the believers.The Archangel Gabriel, upon him be peace, who was party to the conversation, at God's command said on that night: "I bear witness that there is no deity but God and I bear witness that Muhammad is God's Messenger." This gave the glad tidings that all of the Community of Muhammad, upon him be peace and blessings, would testify in the same way until the Last Day.Through recalling this sacred conversation during the seated sections of every canonical Prayer, the meanings of its words become filled with light and gain comprehensiveness.