'Witnessing' in the Bible

For out of the heart come evil thoughts and plans, murders, adulteries, sexual immoralities, thefts, false testimonies, slanders (verbal abuse, irreverent speech, blaspheming).

In this way our testimony about Christ was confirmed and established in you,

when He comes to be glorified in His saints on that day [that is, glorified through the changed lives of those who have accepted Him as Savior and have been set apart for His purpose], and to be marveled at among all who have believed, because our testimony to you was believed and trusted [and confirmed in your lives].

Keep your behavior excellent among the [unsaved] Gentiles [conduct yourself honorably, with graciousness and integrity], so that for whatever reason they may slander you as evildoers, yet by observing your good deeds they may [instead come to] glorify God in the day of visitation [when He looks upon them with mercy].

I, John, your brother and companion in the tribulation and kingdom and patient endurance which are in Jesus, was on the island called Patmos, [exiled there] because of [my preaching of] the word of God [regarding eternal salvation] and the testimony of Jesus Christ.

And they overcame and conquered him because of the blood of the Lamb and because of the word of their testimony, for they did not love their life and renounce their faith even when faced with death.

And then I saw thrones, and sitting on them were those to whom judgment [that is, the authority to act as judges] was given. And I saw the souls of those who had been beheaded because of their testimony of Jesus and because of the word of God, and those who had refused to worship the beast or his image, and had not accepted his mark on their forehead and on their hand; and they came to life and reigned with Christ for a thousand years.