A.T. Robertson Commentary Luke 5:8

"But Simon Peter, when he saw it, fell down at Jesus` knees, saying, Depart from me; for I am a sinful man, O Lord." — Luke 5:8 (ASV)

Fell down at Jesus' knees (προσεπεσεν τοις γονασιν Ιησου). Just like Peter, from extreme self-confidence and pride (verse 5) to abject humilation. But his impulse here was right and sincere. His confession was true. He was a sinful man.