The Holy Spirit was first sent upon the Apostles
50 days after Jesus’ Resurrection and
9 days after His Ascension back into Heaven.

The form of praying a Novena was based on these 9 days.
 

PRAYER TO THE HOLY SPIRIT
TO BE SAID NINE CONSECUTIVE DAYS

O, Holy Spirit, beloved of my soul,
I adore You.
enlighten me, guide me,
strengthen me, console me.
Tell me what I should do.
Give me Your orders.

I promise to submit myself to
all that You desire of me
and accept all that You permit
to happen to me.

Let me only know Your Will.

Amen.