προσέπεσαν [3 verses](3rd pl aor ind act) "Beat upon" is proskopto, which means "to strike against", "to stumble upon", "to encounter friction", "to offend," and "to take offense at." The root koptô means "to smite", "to pound," "to chop," "to cut off," and "to beat one's breast. The prefix means "against" or "towards." -- This word is only used three times by Jesus. Twice in parallel verses to means "stumble upon," even though it is not the common word for "stumble." Once to describe a storm beating against a house in last story in the  Sermon on the Mount. " The word means "strike against" so in the context of walking, it means "stumble upon."