Is it true that the Prophet (peace be upon him) said to one who heard the adhan in a dream before Fajr, "You will enter Paradise," and to one who heard it after Fajr, "You will enter prison"?

This story has no origin attributed to the Prophet, peace and blessings be upon him. What indicates its falsehood is that imprisonment (sijn) was not known during the days of the Prophet, peace and blessings be upon him. Sheikh al-Islam Ibn Taymiyyah clarified that lawful detention (al-habs al-shar'i) is the prevention of a person and restraining him from acting freely, and not imprisonment in a confined place. There was no prison specifically prepared for incarcerating people during the era of the Prophet, peace and blessings be upon him, or Abu Bakr. Rather, this began in the time of Umar ibn al-Khattab when he took a house in Mecca as a prison.