From Parashat Miketz
Arguably, Parashat Miketz is Bereshit's most dramatic chapter. And that is saying quite a lot, especially considering the riveting subject matter contained in each and every one of Genesis’ twelve parshiyot. Do they not comprise episodes and narratives chock-full of esoterica, intrigue, and bafflement that stretch man's imagination, reason, and intellect?
Tucked into Miketz' seventh aliyah where the feverish high pitch blazes, a smaller but important question surfaces. In chapter forty-four, we read Yosef's instruction to his charges d'affaires: ‘And he directed the head of his household saying: “Fill the men's satchels with food...” Along with food, Yosef's assistant was told to stuff silver into their bags. Finally, Yosef had his overseer toss into Binyamin's, the youngest man's belongings, something queer. And also place in one satchel “my goblet, the goblet of silver.”
No sooner had the brothers rode out of town than they were quickly pursued and apprehended. Criminal charges followed. “Why did you act ungratefully? Behold this is [the goblet] from which my master drinks. He divines with it.”
Really?! But the Torah prohibits all forms of black magic.
Fairly, students ask: Was righteous Yosef swayed and influenced by Egyptian culture that regularly practiced voodoo, a milieu that divined galore?
Lest we think that the agent's words were exaggerated, later Yosef himself echoes the exact sentiments when he confronts his brothers, the putative pilferers. “And Yosef said to them: ‘What is this ill-deed that you perpetrated? Did you not know that with this [goblet], I practice witch-craft?”
Here is a plausible explanation. Seemingly, Yosef really only made some insignificant, symbolic, and mostly ceremonial use of the silver goblet. The Sages (BT Chulin 95 b) offer dispensation in certain cases, wherein one's good fortune can be traced to the onset of an association with a particular item or person. This is deemed harmless (and hence not prohibited) as long as one does not make practical decisions based on that association.
Akin to this notion is a Jewish custom of celebrating marriages on Rosh Chodesh or eating particular foods on Rosh Hashana (See Rema Even HaEzer 64:3 and BT Keritot 6a).