St. Margaret Mary Alacoque was a 17th century mystic. She was a Visitation nun. When she started having visions of Jesus, members of her order and theologians did not believe her. Eventually her visions were accepted.
When Jesus appeared to St. Margaret Mary Alacoque, he promise several graces to those who devoted themselves to his Sacred Heart. They would show their devotion by receiving communion on nine consecutive first Fridays.