See the notes at Matthew 27:52-55.
The things which were done - The earthquake, the darkness, and the sufferings of Jesus.
Smote their breasts - In token of alarm, fear, and anguish. They saw the judgments of God; they saw the guilt of the rulers; and they feared the farther displeasure of the Almighty.
47 Now when the centurion saw what was done, he glorified God, saying, Certainly this was a righteous man.
48 And all the people that came together to that sight, beholding the things which were done, smote their breasts, and returned.
49 And all his acquaintance, and the women that followed him from Galilee, stood afar off, beholding these things.