John Gill Commentary Genesis 40:12

"And Joseph said unto him, This is the interpretation of it: the three branches are three days;" — Genesis 40:12 (ASV)

And Joseph said to him, this [is] the interpretation of it , &c.] Of the dream: the three branches [are] three days ; signify three days, or, as Jarchi expresses it, are a sign of three days; which Joseph could know only by divine revelation; for there is no more likeness between branches and days, than between them and months or years, and bid as fair to signify one as the other, if the interpretation depended on similarity, or bare conjecture.