These are the generations of Yaakov: Yosef, being seventeen years old, was feeding the flock with his brothers; and he was a lad with the sons of Bilhah, and with the sons of Zilpah, his father’s wives; and Yosef brought their evil report unto their father.
English: Rabbi Levi said: A person should always wait for a good dream up to twenty-two years, as it is written “Yosef was seventeen years old,” and it is written “And Yosef was thirty years old when he stood before Pharaoh,” which is thirteen years, plus the seven years of plenty and two years of the famine — altogether twenty-two.
On the daf / in context: Berachos 55b discusses the longevity of dream interpretation and derives a maximum waiting period from the span between Yosef’s youthful dreams and their fulfillment.
Type of Learning
Derash on the verse (Bavli sugya) — not a formal named middah of the 13. The numerical span between the two ages of Yosef is used to establish a practical limit.
What Is Learned
One should not abandon hope for the positive realization of a dream for as long as twenty-two years, the interval that elapsed between Yosef’s dreams at seventeen and their fulfillment.