Why did Nabal’s servant think that harm was determined against his master and against all his house?
Nabal’s servant considered his master’s response to be sinful and likely to incur David's wrath. This confirms that David had a right to share in the profit and he was not asking for charity.
17 Sache maintenant et vois ce que tu as à faire, car la perte de notre maître et de toute sa maison est résolue, et il est si méchant qu'on n'ose lui parler.