Nabal delivers a loud and absolute rejection to the messengers, showing deep disrespect for David’s name and honor [ביאור שטיינזלץ, מלבי״ם]. By questioning David's identity and his father's name, Nabal is actually asking why this man is considered important enough to deserve gifts and property [מצודת דוד]. He completely dismisses David’s personal worth as well as his family background [מלבי״ם]. This specific contempt for his lineage stems from the fact that David is a descendant of Ruth the Moabite [רש״י].
Continuing his insult, Nabal complains about a supposed trend of servants breaking away from their masters. The primary approach among commentators is that he is referring to runaway slaves who rebel, painting David as just another simple servant revolting against King Saul [רד״ק, ביאור שטיינזלץ]. Another perspective suggests the concept refers to arrogance, describing servants who elevate themselves above their masters and claim greatness. According to this view, Nabal accuses David of acting superior and therefore feeling entitled to demand a tribute from him [מצודת דוד, מצודת ציון]. Alternatively, this accusation might contain a mocking reference to David's ancestry, targeting those who claim descent from Perez and believe they are naturally destined for the kingship [חומת אנך].
Ultimately, Nabal attacks David with a double insult. First, he claims David is an unknown figure with no respectable lineage. Second, he argues that even David's reputation as a rebel earns him no respect. In the past, rebelling against a king was a rare and notable act, but Nabal claims that rebellious servants have now become a common occurrence. As a result, he concludes that there is absolutely nothing unique about David that justifies granting him honor or wealth [מלבי״ם].