Divine Mercy 187 Jesus said: Call upon My mercy on behalf of sinners; I desire their salvation. When you say this prayer, with a contrite heart and with faith on behalf of some sinner, I will give him the grace of conversion. This is the prayer:
"O Blood and Water which gushed forth from the Heart of Jesus as a Fount of Mercy for us, I trust in you." (Diary 186, 187)
This is not a guarantee of salvation. It is an offer of conversion, which may be rejected. However, if successful, the soul might then convert other souls, who might then convert others again. At your own judgement you may be credited with helping to save thousands.
Wherever you are, in the street or shopping centre, even at work, say this prayer foreach person you see, if that is possible. If the numbers are too great, just say it once for a group.
From all eternity God has planned to place all these people across your path, and it may well be within His infinite will that you should assist them to join Him.
This devotion is suited especially for those who have no other reasonable way to save souls, but is also a great devotion for everyone.