The death of Mohammed is rarely discussed, and it turns out it is a rather embarrassing topic. After Mohammed had besieged the Jewish community of Khaibar in June of 628 and his followers killed quite a number of the residents in battle a treaty was negotiated.
A woman named Zeynab, whose husband had been among those slain, prepared a meal for the prophet as a gift. Mohammed along with one of his friends named Bishr Ibn al-Bara ate a shoulder of lamb she had prepared. Bishr tasted poison in the meat but said nothing because the prophet who had divine guidance from Allah was eating it and said nothing until it was too late. Soon it was realized that they had been poisoned and in a day or two Bishr was dead. Zeynab was dragged before the prophet and interrogated. She explained that because her husband, an uncle and father had been killed by Mohammed's clan she wanted to rid the world of their killer. If he was indeed a prophet she reasoned he would not be harmed. She was handed over to Bishr's family who murdered her.
As a result, according to Muslim sources, Mohammed suffered much pain for the next four years then died. So not only did Allah not reveal to Mohammed about the plot, nor protect him and his friend, but he was put down by not only a woman but a Jewish one at that.
Bukhari 2:617, 3:786, 5:713
Ibn Saad Vol 2, pp 249-252
Tabari 8, pp. 123-124