Why did Omar ibn al-Khattab say to the Messenger of Allah, peace and blessings be upon him, when he was ill: "He is delirious"?

In summary, the aforementioned hadith is about the intensification of the Prophet's illness, peace and blessings be upon him, and his statement: "Bring me a shoulder blade or a slate and inkwell so I may write for you a document after which you will never go astray," and the statement of some, "What is wrong with him? Is he delirious?"

The meaning of "delirious" (yahjur) is the raving that emanates from a sick person. This is impossible for the Prophet, peace and blessings be upon him, because he is infallible, based on the Almighty's saying: "Nor does he speak from [his own] inclination," and the Prophet's saying, peace and blessings be upon him: "Indeed, I do not say but the truth, whether in anger or pleasure."

The statement "Is he delirious?" was not uttered by Umar, but rather by some Companions as an interrogative and a refutation of those who hesitated to obey the Prophet's command, as if to say: "How can you hesitate to obey his command? Do you think he is delirious? Obey his command, for he speaks nothing but the truth."

Scholars differed regarding what the Prophet intended by the writing. Some said he intended to stipulate the succession, while others said he intended to clarify important rulings. He intended to write when it seemed beneficial to do so, then it became apparent that abandoning it was more beneficial. If what he intended was something indispensable, he would not have abandoned it.

Umar's statement: "The Book of Allah is sufficient for us" was a response to those who disputed with him, and he intended to alleviate the burden on the Prophet, peace and blessings be upon him, and to draw attention to the fact that the religion had been perfected with the Book of Allah, and that the Ummah would not go astray as long as it adhered to it. This indicates Umar's profound understanding and keen insight.