Acts of the Apostles

[...] The first book I wrote, Theophilus, concerned all that Jesus began both to do and to teach, [...]

Acts of the Apostles: chapter 1, verse 1

Chapter 18, verses 18-19

¹⁸ Paul, having stayed after this many more days, took his leave of the brothers, and sailed from there for Syria, together with Priscilla and Aquila. He shaved his head in Cenchreae, for he had a vow.

¹⁹ He came to Ephesus, and he left them there