In the beginning of Act IV, Scene 3, Juliet is alone with the Nurse. She has just agreed to marry Count Paris and the Nurse is helping her with her wedding clothes. In reality, however, she plans on faking her death by drinking a potion mixed by Friar Laurence in order to avoid the marriage with Paris because she is already married to Romeo. She suggests to the Nurse that she is in great need of "orisons," another term for prayers, because she will be guilty of a great sin by marrying another man while her first husband is still alive. She is also guilty of lying to her parents about her relationship with Romeo. She tells the Nurse,

Ay, those attires are best. But, gentle nurse,
I pray thee leave me to myself tonight,
For I have need of many orisons
To move the heavens to smile upon my state,
Which, well thou knowest, is cross and full of sin.

In Act IV, Scene 3,  Juliet tells the nurse, "but, gentle nurse, I pray thee leave me to myself tonight; for I have need of many orisons to move the heavens to smile upon my state, which though knowest, is cross and full of sin."  The word for prayers is orisons which comes from the French word oraisons.