This Saturday is the Vigil of Pentecost. Traditionally, this was a solemn vigil in the same vein as the sacred Paschal Vigil, though it has long since been trimmed down in length. For this reason, traditionally, Catholics fasted prior to Mass as they prepared for the celebration of the coming of the Holy Spirit in time.
Ant. When I shall be sanctified in you, I will gather you together out of all the countries: and I will pour clean water upon you and you shall be cleansed from all your uncleanness: and I will give you a new spirit, alleluia, alleluia.
V. I will bless the Lord at all times; His praise shall be always in my mouth.
V. Glory be...
Ant. Send forth Thy Spirit and they shall be created, and Thou shalt renew the face of the earth. May the glory of the Lord endure forever, alleluia.
Ant. On the last day of the festival, Jesus said: Fountains of living water shall flow out of the bosom of him who believes in Me: now this He said of the Spirit which they would receive who believe in Him, alleluia, alleluia.