Prayer to Sacred Shoulder Wound
O Loving Jesus, meek Lamb of God, I, miserable sinner, salute and worship the most Sacred Wound of Thy Shoulder on which Thou didst bear Thy heavy Cross which so tore Thy Flesh and laid bare Thy Bones as to inflict on Thee an anguish greater than any other wound of Thy Most Blessed Body.
I adore Thee, O Jesus most sorrowful; I praise and glorify Thee, and give Thee thanks for this most sacred and painful Wound, beseeching Thee by that exceeding pain, and by the crushing burden of Thy heavy Cross to be merciful to me, a sinner, to forgive me all my mortal and venial sins, and to lead me on towards Heaven along the Way of Thy Cross. Amen.
Eternal Father, I offer Thee the Wounds of our Lord Jesus Christ to heal the wounds of our souls. My Jesus, pardon and mercy through the merits of Thy Sacred Wounds.

Can this prayer be purchased?
Here are some prayer cards:
https://m.catholicspringtime.com/page/subpage/traditional_Catholic_prayers/Shoulder-Wound-of-Christ-Prayer-Card.htm
Please note, I don’t think the alleged message given to St. Bernard is verified or Church approved. You’d have to research that.
Best wishes,
JMJ