What does Macbeth see that supports the idea he feels guilty about killing banquo?

Macbeth sees the ghost of Banquo at a feast. The ghost appears to sit in Macbeth's chair, causing Macbeth to become distraught and paranoid. He tries to dismiss the vision, but it persists, and Macbeth becomes increasingly agitated and unhinged. The appearance of Banquo's ghost, as well as Macbeth's reaction to it, suggests that Macbeth is feeling guilt and remorse for killing Banquo.