w/salaam,
There are several versions of his last sermon, e.g.
"...I have left among you the Book of Allah, and if you hold fast to it, you would never go astray...."
See Sahih Muslim, Book of Hajj, Book 7 , Number 2803
None knows the future, including Muhammad (5:109, 6:50, 7:188, 10:20, 11:31, 18:110, 27:65, 46:9, 81:24). Only God knows the future and this knowledge can be attained only through divine revelations/signs (3:44, 3:179, 11:49, 12:102, 30:2, 72:26-28).
And the icing on the cake, from the Traditional Ahadith, Sahih Bukhari:
Volume 9, Book 93, Number 477:
Narrated Masruq:
'Aisha said, "If anyone tells you that Muhammad has seen his Lord, he is a liar, for Allah says: 'No vision can grasp Him.' (6.103) And if anyone tells you that Muhammad has seen the Unseen, he is a liar, for Allah says: "None has the knowledge of the Unseen but Allah."