When they heard this they were cut to the heart, and they said to Peter and the other apostles, “Brothers, what are we to do?”
In context
35until I make your enemies a footstool for your feet.’ 36So let all the house of Israel know for certain: God has made him both Lord and Christ, this Jesus whom you crucified.” 37When they heard this they were cut to the heart, and they said to Peter and the other apostles, “Brothers, what are we to do?” 38Peter answered them, “Repent, and let each of you be baptized in the name of Jesus Christ for the forgiveness of your sins, and you will receive the gift of the Holy Spirit. 39The promise is for you and for your children and for all who are far away, for everyone the Lord our God calls to himself.”