Acts 14:3

14:3 So they stayed there for a considerable time, speaking out courageously for the Lord, who testified to the message of his grace, granting miraculous signs and wonders to be performed through their hands.

John 5:37

5:37 And the Father who sent me has himself testified about me. You people have never heard his voice nor seen his form at any time,

Hebrews 2:4

2:4 while God confirmed their witness with signs and wonders and various miracles and gifts of the Holy Spirit distributed according to his will.