Or HaChaim on Genesis 44:5/אור החיים על בראשית מ״ד:ה׳

1 הלא זה אשר ישחה אדוני בו "Is this not (the goblet) which my master drinks out of?" There was no need to mention that the speaker was the man who had deposited the goblet in the pouch of Benjamin. Neither was there a need to inform the reader that he spoke about the goblet. He merely wanted to explain why the theft of this goblet had been discovered immediately. The reason was that Joseph drank from that goblet all the time. The adjutant added that his master used this goblet to divine the future. It was clear then that the reason the brothers stole that goblet was to deprive Joseph of the knowledge the goblet could provide. The adjutant had no reason to suspect anyone else of the theft of this goblet. He repeated the word נחש ינחש both in the past and in the future to support his suspicion by reminding the brothers that they had already observed his master use the goblet to reveal the past. He had divined at that time already that the brothers would steal the goblet.

2הרעוחם אשר עשיתם "What you have done is bad!" Why did the adjutant add these words after having already accused the brothers of repaying good with evil? Is there anything worse than repaying good with evil?

3Perhaps the adjutant wanted to demolish the good image of themselves the brothers had created when they brought back the money they had found in their bags after arriving home in Canaan. After all, the adjutant was the very person whom they had told that they had found that money and had brought it back with them. As a result, logic should convince him that the brothers had already established their honesty beyond doubt. In fact the brothers were going to use that argument presently. The words: "you have done something bad," were designed to demolish their argument even before they could present it. Henceforth the adjutant would not allow his suspicions against them to be influenced by invoking their past actions. The brothers having returned the money had been motivated by something other than their honesty.

4The adjutant may even have hinted that the fact that the brothers had brought back the money had been a clever ruse to establish their credibility as honest and upright people, all the while providing a smokescreen for the theft of other more precious objects. The goblet was merely one such object.