In the original Greek the word translated as "Peter" is "Πέτρος" (Petros) and that translated as "rock" is "πέτρα" (petra), two words that, while not identical, give an impression of one of many times when Jesus used a play on words. Furthermore, since Jesus presumably spoke to Peter in their native Aramaic language, he would have used "kepha" in both instances. The Peshitta Text and the Old Syriac text use the word "kepha" for both "Peter" and "rock" in . says Jesus called Simon "Cephas", as does Paul in some letters. He was instructed by Christ to strengthen his brethren, i.e., the apostles. Peter also had a leadership role in the early Christian church at Jerusalem according to The Acts of the Apostles chapters 1–2, 10–11, and 15.