Or HaChaim on Genesis 40:14/אור החיים על בראשית מ׳:י״ד

1 כי אם זכרתני, "if you would only remember me, etc." Perhaps Joseph made his favourable interpretation conditional on the chief of the butlers remembering him. The reason that Joseph placed his hopes in the chief butler was that the Jewish people have been compared to a vine, as has been pointed out in Chulin 92. והנה גפן לפני, "there was a vine in front of me;" Joseph reasoned that if the dream only concerned matters related to the chief butler, all that needed to be shown in the dream was that the chief butler held Pharaoh's cup in his hand. He reasoned that the additional information referred to himself in jail; when the Torah goes on to describe how that vine was blooming, Joseph took this as a sign that the vine would prosper; he took the word נצה to mean that his rise would be progressively higher. This is why when he explained the dream to the chief butler he added that it was important that the chief butler remember Joseph during better times.

2In due course Joseph was proven right, for ultimately the chief butler did recall him and this started Joseph's dramatic rise to power. The reason Joseph was punished was because he imagined that his own advancement would depend on the goodwill of the chief butler. While G'd did use the chief butler as His instrument in advancing Joseph's fortune, the chief butler did not act voluntarily. He was prompted by fear to recall his days in jail (41,12). Joseph had to be taught the lesson not to rely on man.