Hastings' Dictionary of the Bible (1898)
WIT'NESS, one who gives testimony. Two or more witnesses were required by the Mosaic Law in judicial investigations, Deut 17:6-7; and when the sentence of stoning was pronounced, they were required to commence the process of execution. Acts 7:58. A false witness was to suffer that penalty which his testimony might have brought over the accused. The witness of the Spirit with our spirit, Rom 8:16, denotes the consciousness, more or less distinct, of the operations of the Spirit upon the mind, enlightening the understanding and inclining the subject of them to do the will of God.
John often exhibits the gospel in the light of a testimony, 1 John 5:9, and Christ himself is called "the faithful and true Witness," Rev 1:5; Num 3:14, not only to the glory and perfection of the Father, but also to his own divine mission and to the universality and perpetuity of his kingdom.