From 1931 to 1938, our Lord instructed to Sister (now Saint)
Faustina:
"My daughter, speak to the wole world of My incomprensible Mercy. I
desire that the Feast be a refuge and a shelter for all souls,
especially for poor sinners. The very depths of My mercy will be
opened on that day. I will pour out a sea of graces upon those
souls that will approach the font of My mercy.
"Those who go to confession and receive Holy Communion on Mercy
Sunday, the first Sunday after Easter, will obtain complete
remission of sins and punishment. Let no soul fear to come to Me,
even though its sins be as scarlet. Tell ailing mankind to draw
close to My merciful heart and I will fill it with peace. Mankind
will not find peace until it turns with confidence to My
mercy."