Acts 1:5

Overview - Acts 1
1	Christ, preparing his apostles to the beholding of his ascension, gathers them together unto the mount Olivet, commands them to expect in Jerusalem the sending down of the Holy Ghost, promises after a few days to send it, and ascends into heaven in their sight.
10	After his ascension they are warned by two angels to depart, and to set their minds upon his second coming.
12	They accordingly return, and, giving themselves to prayer, choose Matthias apostle in the place of Judas.

Acts 1:5  (King James Version)
For John truly baptized with water; but ye shall be baptized with the Holy Ghost not many days hence.