This Jesus (touton ton Iēsoun). Many of the name “Jesus,” but he means the one already called “the Nazarene” (Act 2:22) and foretold as the Messiah in Psa 16:1-11 and raised from the dead by God in proof that he is the Messiah (Act 2:24, Act 2:32), “this Jesus whom ye crucified” (Act 2:36). Other terms used of him in the Acts are the Messiah, Act 2:31, the one whom God “anointed” (Act 10:38), as in Joh 1:41, Jesus Christ (Act 9:34). In Act 2:36 God made this Jesus Messiah, in Act 3:20 the Messiah Jesus, in Act 17:3 Jesus is the Messiah, in Act 18:5 the Messiah is Jesus, in Act 24:24 Christ Jesus.
Whereof (hou). Or “of whom.” Either makes sense and both are true. Peter claims the whole 120 as personal witnesses to the fact of the Resurrection of Jesus from the dead and they are all present as Peter calls them to witness on the point. In Galilee over 500 had seen the Risen Christ at one time (1Co 15:6) most of whom were still living when Paul wrote. Thus the direct evidence for the resurrection of Jesus piles up in cumulative force.