Stephen started to answer the high priest’s accusations by talking about Abraham.

Acts 7:1-4

7 Then the high priest asked Stephen, “Are the things that these people are saying about you(sg) true?” 2 Stephen replied, “Fellow Jews and respected leaders, please listen to me! The glorious God whom we(inc) worship appeared to our ancestor Abraham while he was still living in Mesopotamia region, before he moved to Haran town. 3 God said to him, ‘Leave this land where you (sg) and your relatives are living, and go into the land to which I will lead you.’ 4 So Abraham left that land, which was also called Chaldea, and he arrived in Haran and lived there. After his father died, God told him to move to this land in which you and I are now living.”