Albert Barnes Commentary Acts 8:35

"And Philip opened his mouth, and beginning from this Scripture, preached unto him Jesus." — Acts 8:35 (ASV)

Opened his mouth. See Matthew 5:2.

At the same Scripture. Taking this as a text to be illustrated.

Preached unto him Jesus. Showed him that Jesus of Nazareth exactly answered the prophet's description; and that the prophet therefore referred to the Messiah, and that this Messiah was Jesus of Nazareth. How far Philip detailed the circumstances of the life and death of Christ is unknown. What follows also shows that he stated the design of baptism, and the duty of being baptized.