And Joseph said unto him, This {d} is the interpretation of it: The three branches are three days:

(d) He was reassured by the spirit of God, that his interpretation was true.

Jamieson-Fausset-Brown Bible Commentary

12-15. Joseph said, . This is the interpretation-Speaking as an inspired interpreter, he told the butler that within three days he would be restored to all the honors and privileges of his office; and while making that joyful announcement, he earnestly bespoke the officer's influence for his own liberation. Nothing has hitherto met us in the record indicative of Joseph's feelings; but this earnest appeal reveals a sadness and impatient longing for release, which not all his piety and faith in God could dispel.

Matthew Henry's Concise Commentary

40:1-19 It was not so much the prison that made the butler and baker sad, as their dreams. God has more ways than one to sadden the spirits. Joseph had compassion towards them. Let us be concerned for the sadness of our brethren's countenances. It is often a relief to those that are in trouble to be noticed. Also learn to look into the causes of our own sorrow. Is there a good reason? Is there not comfort sufficient to balance it, whatever it is? Why art thou cast down, O my soul? Joseph was careful to ascribe the glory to God. The chief butler's dream foretold his advancement. The chief baker's dream his death. It was not Joseph's fault that he brought the baker no better tidings. And thus ministers are but interpreters; they cannot make the thing otherwise than it is: if they deal faithfully, and their message prove unpleasing, it is not their fault. Joseph does not reflect upon his brethren that sold him; nor does he reflect on the wrong done him by his mistress and his master, but mildly states his own innocence. When we are called on to clear ourselves, we should carefully avoid, as much as may be, speaking ill of others. Let us be content to prove ourselves innocent, and not upbraid others with their guilt.