A few other authorities read (with variations) +V7+W[There are three that testify in heaven, the Father, the Word, and the Holy Spirit, and these three are one. +V8+WAnd there are three that testify on earth:]
Other ancient authorities read [in the Son]
New Revised Standard Version Bible, copyright 1989, Division of Christian Education of the National Council of the Churches of Christ in the United States of America. Used by permission. All rights reserved.
(New Revised Standard Bible Version Online)