Dream question

A dream question (Hebrew: 'She'elat Halom') is a practice of divination whereby a person attains a prophetic state while dreaming, receiving a divine answer to a question meditated on before sleep. 
The early medieval master Hai Gaon notes a method for attaining a dream question involving fasting, purification, and meditation on a text. Based on comments by Abraham ibn Ezra 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 said to represent the true name of God. 
In their autobiographical writings from the early 17th century, both mystic Hayyim Vital and rabbi Leon of Modena claim matter-of-factly to have asked a dream question.