A dream question is a practice of divination

Divination

Divination is the attempt to gain insight into a question or situation by way of an occultic standardized process or ritual...

 whereby a person attains a prophetic

Prophecy

Prophecy is a process in which one or more messages that have been communicated to a prophet are then communicated to others. Such messages typically involve divine inspiration, interpretation, or revelation of conditioned events to come as well as testimonies or repeated revelations that the...

 state while dreaming, receiving a divine answer to a question meditated on before sleep.

The early medieval master Hai Gaon

Hai Gaon

Hai ben Sherira , was a medieval Jewish theologian, rabbi and scholar who served as Gaon of the Talmudic academy of Pumbedita during the early 11th century. He was born in 939 and died on March 28, 1038...

 notes a method for attaining a dream question involving fasting, purification, and meditation on a text. Based on comments by Abraham ibn Ezra

Abraham ibn Ezra

Rabbi Abraham ben Meir Ibn Ezra was born at Tudela, Navarre in 1089, and died c. 1167, apparently in Calahorra....

 and others, scholar Moshe Idel has identified this text with Exodus 14:19-21, each verse of which contains 72 consonants alluding to a mystical series of Hebrew letters

Gematria

Gematria or gimatria is a system of assigning numerical value to a word or phrase, in the belief that words or phrases with identical numerical values bear some relation to each other, or bear some relation to the number itself as it may apply to a person's age, the calendar year, or the like...

 said to represent the true name of God.

In their autobiographical writings from the early 17th century, both mystic Hayyim Vital

Hayyim ben Joseph Vital

Hayyim ben Joseph Vital was a rabbi in Safed and the foremost disciple of Isaac Luria. He recorded much of his master's teachings...

 and rabbi Leon of Modena

Leon of Modena

Leon Modena or Yehudah Aryeh Mi-modena was a Jewish scholar born in Venice of a notable French family that had migrated to Italy after an expulsion of Jews from France.-Life:...

claim matter-of-factly to have asked a dream question.