In 1688, during an apparition to Saint Margaret Mary, Our Lord Jesus Christ promised the grace of the Holy Death to those who would receive Holy Communion on the first Friday of the month, nine months in a row. This was called The Great Promise.
The 12 promises of the Sacred Heart of Jesus
1. I will give them all the graces necessary in their state of life.
2. I will establish peace in their homes.
3. I will comfort them in all their afflictions.
4. I will be their secure refuge during life, and above all, in death.
5. I will bestow abundant blessings upon all their undertakings.
6. Sinners will find in my Heart the source and infinite ocean of mercy.
7. Lukewarm souls shall become fervent.
8. Fervent souls shall quickly mount to high perfection.
9. I will bless every place in which an image of my Heart is exposed and honored.
10. I will give to priests the gift of touching the most hardened hearts.
11. Those who shall promote this devotion shall have their names written in my Heart.
12. I promise you in the excessive mercy of my Heart that my all-powerful love will grant to all those who receive Holy Communion on the First Fridays in nine consecutive months the grace of final perseverance; they shall not die in my disgrace, nor without receiving their sacraments. My divine Heart shall be their safe refuge in this last moment.
Reparatory Communions on the First Fridays of the month
The Twelfth Promise was inserted in full in the Bull of Canonization of St. Margaret Mary on May 13, 1920, by Pope Benedict XV. He thus wanted to encourage the practice of reparatory communions on the nine first Fridays of the month, in honour of the Sacred Heart.