Is there not a cause? — David answers his jealous and over-bearing elder brother with all gentleness and forbearance, but he does not cease to make his inquiries of the soldiers respecting the giant, nor does he refrain from loudly expressing his astonishment at such a public insult to the God of Israel being allowed to continue for so many days. The Hebrew here would be more literally rendered, “Is it not a word,” or “It was only a word,” thus deprecating his elder brother’s anger. “What have I done? It was but a mere word. I was only speaking with holy anger about this impious challenge of the Philistine; nothing more.” The ancient versions thus understand this clause.
If we render as the Authorised Version, then the sense is quite clear. “You seem bitterly displeased with my zeal in this matter, but surely, is there not a good cause for my passionate emotion here — such an insult to our God?”