A prophet proves himself through accurate predictions. If all statements are consistently accurate, he is accepted.
Question 2
If a prophet predicts punishment and it doesn't happen, is he false?
Doom prophecies can be reversed through repentance (like Yonah/Nineveh). But good prophecies that fail = false prophet.
Question 3
What distinguishes a prophet from a sorcerer?
Sorcerers are sometimes right, sometimes wrong. A true prophet's words are 100% reliable.
Question 4
Can a recognized prophet vouch for another person as a prophet?
When a recognized prophet declares another person is a prophet, that person is accepted without further testing. Moshe vouched for Yehoshua and all Israel accepted.
Question 5
If a prophet predicts something good and it doesn't happen, what does that mean?
The Rambam rules: God doesn't retract a promise of good. If a positive prophecy fails, the prophet is definitively false.