A person who tells about what he or she has seen or experienced, often in a court of law. The word "witness" may also refer to the testimony the person has given.
Witness in the Old Testament
In the legal procedure outlined in the Old Testament, one witness was not adequate for personal testimony against a person. Two or three witnesses were required (Deuteronomy 17:6; 19:15). Jewish law includes this principle, and the New Testament repeats it (compare Matthew 18:16; 2 Corinthians 13:1).
The truth of testimony is so important that the ninth commandment forbids false witness (Exodus 20:16; Deuteronomy 5:20; compare Mark 10:19; Luke 18:20). The book of Proverbs often warns against false witness (for example, Proverbs 6:19; 14:5; 25:18). Yet, some people did give false testimony. (Psalms 27:12; 35:11). In some cases, more than one false witness was brought to bring about the death of an innocent person. The story of Naboth and his vineyard is well known for its injustice. King Ahab's wife Jezebel bribed two men to bear false witness against Naboth so he would be stoned to death. Then Jezebel's wicked husband could take the vineyard he greatly desired (1 Kings 21).
Witnesses could be tested by the judges. If an accuser was false, that person received the punishment he had sought to do to the defendant (Deuteronomy 19:16–21). Proverbs also speaks of the punishment of the false witness (Proverbs 19:5, 9; 21:28).
The Old Testament records several accounts of legal proceedings in which witnesses are mentioned. Most of these involve the purchase or transfer of property. Ruth 4:7–12 relates the redemption of a field from Naomi by Boaz. Isaiah found "reliable witnesses" concerning a property title written on a large tablet (Isaiah 8:1–2). To confirm the prophecy of the return of the exiles from Babylon, Jeremiah bought and paid for a field in the presence of witnesses. The witnesses also signed the deed for the property (Jeremiah 32:6–15).
At the end of his farewell message at Shechem, Joshua declared that the Israelites themselves were witnesses. They had chosen to serve the Lord. Joshua then he set up a large stone and declared that it also was a witness (Joshua 24:22–27). The people of Israel themselves were declared God’s witnesses (Isaiah 43:10; 44:8–9). They were witnesses to the existence of God, to his uniqueness, holiness, power, and love. When the Israelites failed to acknowledge his uniqueness and holiness and turned to idolatry, he sent them into captivity. He had warned them, for they had failed in their witness and had given opportunity for the enemies of God to blaspheme (speak badly about God).
Witness in the New Testament
In the New Testament the various words for witness are mainly related to the verb martureo, meaning "to bear witness, be a witness." The word "martyr" shows the ultimate form of witness. Christians have sacrificed their lives because of their witness for Jesus Christ.
John the Baptist was both a witness and a martyr. As the forerunner of the Messiah, his mission was to bear witness to the light and to identify the Lamb of God (John 1:7–8, 19–36). The followers of Jesus, and particularly the 12 apostles, were witnesses to the person and character of Jesus. They knew him, heard his teachings and observed his miracles. Three were witnesses of his miraculous change in appearance (know as transfiguration, Matthew 17:1–2; 2 Peter 1:17–18). Many were witnesses to his resurrection (Luke 24:48; 1 Corinthians 15:4–8). At the time of his ascension, the disciples were commissioned to be his witnesses (Acts 1:8).