2 Samuel 18:9
And Absalom met the servants of David. And Absalom rode upon a mule, and the mule went under the thick boughs of a great oak, and his head caught hold of the oak, and he was taken up between the heaven and the earth; and the mule that was under him went away.
Absalom had been pursuing David, but after his defeat he was fleeing when his head was caught in the branches of a great tree. His mule ran on without him, leaving him helplessly suspended in midair between heaven and earth and exposed to his enemies. This marks the end of his rebellion in his defeat and death.
His death is part of the bitter punishment and consequences David suffered for his own wrongdoing and sin. His downfall brought David great distress.