The devotion to the Heart of Jesus is ancient. We find the first traces of it in the XI-XII centuries. It seems to flow from devotion to the wounds of Christ, especially on his side. Then, from the wound on the side, we went to the wound of his heart, since the wound on the side was understood as the wound of the heart. The devotion to the Heart of Jesus then emerged as a distinct devotion from the middle of the 15th century. Until then, this devotion had remained an aspect or an extension of the devotion to the Passion.
Among the prayers of Mother Thérèse, we find a prayer to the wounds of Jesus, invocations to the Sacred Heart and a very small manuscript booklet with a “Prière et Convention au Sacré Cœur”.
To the Holy Wounds of Jesus
O Jesus, I adore Your Sacred Wounds, like many sources from which flows on me the salutary Balm which must heal mine. Deign, I implore you, to apply to me the infinite merits of this divine Liniment and to heal all the wounds that sin has done to my soul. Amen.
Invocations to the Sacred Heart
Some sisters recounted her use of it:
She almost always kept the Sisters at recreation, and made us pick, from her little bag, a note with an invocation to the Sacred Heart. 
From time to time, during the day, she made me pick an invocation to the Sacred Heart, like these: patience of the Heart of Jesus, do not tire of my heart… reign of the Heart of Jesus, establish Yourself in my heart… mercy of the Heart of Jesus, forgive my heart, saying to me: it will help you to think of God; it helps me a lot to keep myself united to Him. 
Patience of the Heart of Jesus, Do not tire of my heart.
Presence of the Heart of Jesus, Attach my heart.
Providence of the Heart of Jesus, Watch over my heart.
Zeal of the Heart of Jesus, Devour my heart.
Equity of the Heart of Jesus, Regulate my heart.
Knowledge of the Heart of Jesus, Teach my heart.
Charity of the Heart of Jesus, Diffuse in my heart.
Light of the Heart of Jesus, Illuminate my heart.
Domain of the Heart of Jesus, Subdue my heart.
Love of the Heart of Jesus, Set my heart on fire.
Justice of the Heart of Jesus, Do not abandon my heart.
Will of the Heart of Jesus, Dispose of my heart.
Mercy of the Heart of Jesus, Forgive my heart.
Wound of the Heart of Jesus, Heal my heart.
Liberality of the Heart of Jesus, Enrich my heart.
Strength of the Heart of Jesus, Support my heart.
Beauty of the Heart of Jesus, Ravish my heart.
Sweetness of the Heart of Jesus, Pacify my heart.
Glory of the Heart of Jesus, Fill my heart.
Sufferings of the Heart of Jesus, Touch my heart.
Immutability of the Heart of Jesus, Secure my heart.
Poverty of the Heart of Jesus, Detach my heart.
Wisdom of the Heart of Jesus, Direct my heart.
Holiness of the Heart of Jesus, Sanctify my heart.
Prayer and ‘Convention’ to the Sacred Heart
The prayer, or rather the set of prayers, that follows is not from Mother Thérèse. They come from various books of piety of the 19th century. They have been copied and constitute a small handwritten booklet.
Stop!… the Heart of Jesus
Christ is here.
Loved, cherished, known,
adored, served, O Sacred Heart
and glorified be of Jesus,
eternally, the save us:
Sacred Heart we
of Jesus perish.
Sweet Heart of Jesus, be
my love. (300 days indulgence)
Prayer and ‘Convention’ with the
Sacred Heart of Jesus
My God, I promise you, until my last sighing, whenever my heart beats, whenever I pass before a church or cross, whenever I am tempted, whenever I meet someone, going, coming, working, recreating, the intention to offer you, as many times as there are seconds in the day, grains of sand on the earth and atoms in the air, the merits of Our Lord Jesus Christ, his fasts, his penances, his painful passion, his adorable blood, his humiliations and his death; to ask you as many times for forgiveness of my sins, of those of my parents, of my friends and enemies, of all those of the infidels, of the heretics, of the Jews, of the evil Christians; to ask you for my conversion and that of all the existing sinners now and forever; to ask you for the exaltation of the Church; the fulfilment of your adorable will on earth and in heaven; the fulfilment of your adorable will on earth and in heaven [the repetition is from Mother Thérèse]; the acquisition of all virtues and in particular ……. ; and finally the grace of a good death; for the deliverance of souls from purgatory, especially the most abandoned in favor of which I desire to gain all the indulgences attached to the good works that I will do in the course of this day. I would like to thank you as many times in my name, and in the name of my parents, in the name of all the men who have been, who are, and will be forever; graces received and to be received, known and unknown, from the natural and supernatural benefits you have filled me, of which you fill me every day, and of which you will fill me to the end, I and all those who have been my own, who will be my own forever; to thank you for waiting so long for me and all the poor sinners to repent, and for forgiving me so many times. In a word, I intend to make the rest of my life a long act of atonement, thanksgiving, adoration, impetration, a long act of love. May I, O my God, make reparation by this all the time I have lost and give you back as much glory as I could have taken from you.
My Jesus, mercy. (100 days indulgence)
Sweet Heart of Mary, be my salvation. (300 days of indulgence)
Saint Joseph, watch over us.
Holy Virgin, protect us.
Saint Michael and all the Holy Angels, guard us.
 Sr Françoise Elliex.
 Sr Agarithe, 1887.