There's a strange Rashi that's bothered me for a while.
The sar hamashkim described Yosef to Pharaoh.
וְשָׁ֨ם אִתָּ֜נוּ נַ֣עַר עִבְרִ֗י עֶ֚בֶד לְשַׂ֣ר הַטַּבָּחִ֔ים וַנְּ֨סַפֶּר־ל֔וֹ וַיִּפְתָּר־לָ֖נוּ אֶת־חֲלֹמֹתֵ֑ינוּ אִ֥ישׁ כַּחֲלֹמ֖וֹ פָּתָֽר׃
A Hebrew youth was there with us, a servant of the chief steward; and when we told him our dreams, he interpreted them for us, telling each of the meaning of his dream.
Rashi goes through his descriptions and seemingly inserts what the intention was behind each adjective. One that caught my eye was
עבד וְכָתוּב בְּנִמוּסֵי מִצְרַיִם, שֶׁאֵין עֶבֶד מוֹלֵךְ וְלֹא לוֹבֵשׁ בִּגְדֵי שָׂרִים:
עבד a slave — and it is written in the laws of Egypt that a slave may neither become a ruler nor dress in princely robes (Genesis Rabbah 89:7).
The other descriptions also seem to be telling Pharaoh not to promote him, but this one is the most explicit. Why would the sar hamashkim think Pharaoh would make Yosef a ruler? It's one thing to predict Pharaoh rewarding Yosef for solving the dream puzzle, but no one knew yet what Yosef would say. He ended up describing a nationwide calamity that would occur and Pharaoh appointed Yosef in charge to avoid it. But how could the sar hamashkim have predicted that? What was he driving at, reminding Pharaoh that Yosef can't become a ruler?