'Testifying' in the Bible

Now when Silas and Timothy arrived from Macedonia, Paul became wholly absorbed with proclaiming the word, testifying to the Jews that Jesus was the Christ.

testifying to both Jews and Greeks about repentance toward God and faith in our Lord Jesus.

I have experienced help from God to this day, and so I stand testifying to both small and great, saying nothing except what the prophets and Moses said was going to happen:

They set a day to meet with him, and they came to him where he was staying in even greater numbers. From morning until evening he explained things to them, testifying about the kingdom of God and trying to convince them about Jesus from both the law of Moses and the prophets.