Creon declared that Polyneices couldn't be buried by anyone. He declared this while also declaring his kingship and rightful heir to the throne. Demanding loyalty from his followers and giving a tone of excessive pride.
The sentry told Creon about Polyneices being honored and Creon took his anger out on the Sentry. He despised the messenger for telling him the news, and couldn't stand looking at him or even hearing his voice. Even though the sentry made things right.
The sentry gave Creon the person who buried Polyneices and it relieved his pain a little bit but he was still very upset.