Margaret Mary Alacoque whose Feast Day is today 16th October said that in her apparitions Jesus promised these blessings to those who practice devotion to his Sacred Heart.
I will give them all the graces necessary for their state of life.
I will give peace in their families.
I will console them in all their troubles.
I will be their refuge in life and especially in death.
I will abundantly bless all their undertakings.
Sinners shall find in my Heart the source and infinite ocean of mercy.
Tepid souls shall become fervent.
Fervent souls shall rise speedily to great perfection.
I will bless those places wherein the image of My Sacred Heart shall be exposed and venerated.
I will give to priests the power to touch the most hardened hearts.
Persons who propagate this devotion shall have their names eternally written in my Heart.
In the excess of the mercy of my Heart, I promise you that my all powerful love will grant to all those who will receive Communion on the First Fridays, for nine consecutive months, the grace of final repentance: they will not die in my displeasure, nor without receiving the sacraments; and my Heart will be their secure refuge in that last hour.