“They went to the upper room…All these devoted themselves with one accord to prayer; together with some women, and Mary the mother of Jesus, and his brothers.”
–Acts 1:13-14
The Pentecost novena was instituted by Christ Himself on the day of His Ascension when He sent His Apostles back to Jerusalem to pray for nine days for the coming of the Holy Spirit. On the tenth day, the Holy Spirit descended on them, empowering them to be witnesses to the ends of the earth.