According to the prophet Jeremiah, Urijah was a man who spoke God's messages, just like Jeremiah did. He told the people that something bad would happen to their city and land because they were not listening to God.
Jeremiah 26:20: And there was also a man that prophesied in the name of the LORD, Urijah the son of Shemaiah of Kirjathjearim, who prophesied against this city and against this land according to all the words of Jeremiah:
Amos claims he was not a prophet or a prophet's son, highlighting the unconventional calling of prophets, contrasting the formal recognition of Uriah as a prophet in Jeremiah 26:20.
Amos 7:14: Then answered Amos, and said to Amaziah, I [was] no prophet, neither [was] I a prophet's son; but I [was] an herdman, and a gatherer of sycomore fruit: [sycomore...: or, wild figs]