Acts 4:20

We cannot but speak. The Greek emphasizes the pronoun “we.” They, as Jesus’ apostles, had been especially commissioned to bear witness to Him (Matt. 28:19, 20; Acts 1:8).

Have seen and heard. The apostles’ testimony was grounded on their personal experiences with Jesus. Many years later, in their epistles, both Peter and John emphasized the importance of their having been eyewitnesses to the truths they taught (2 Peter 1:16-18; 1 John 1:1-3). For the Christian today personal experience with the presence of Christ in his life constitutes one of the most convincing evidences of the practical reality of Christian truth.