John Calvin Commentary Acts 2:37

"Now when they heard [this,] they were pricked in their heart, and said unto Peter and the rest of the apostles, Brethren, what shall we do?" — Acts 2:37 (ASV)

They were pricked in heart. Luke now declares the fruit of the sermon, so that we may know that the power of the Holy Ghost was not only manifested in the diversity of tongues, but also in the hearts of those who heard. And he notes a double fruit: first, that they were touched with the feeling of sorrow; and, secondly, that they were obedient to Peter’s counsel.

This is the beginning of repentance, this is the entrance to godliness: to be sorry for our sins, and to be wounded with the feeling of our miseries. For as long as people are careless, they cannot give such heed to doctrine as they ought. And for this reason the word of God is compared to a sword (Hebrews 4:12), because it mortifies our flesh, so that we may be offered to God for a sacrifice.

But readiness to obey must be added to this pricking in heart. Cain and Judas were pricked in heart, but despair kept them back from submitting themselves to God (Genesis 4:13; Matthew 27:3). For the mind, being oppressed with horror, can do nothing else but flee from God.

And surely, when David affirms that a contrite spirit and a humble heart are a sacrifice acceptable to God, he speaks of voluntary pricking, since there is fretting and fuming mixed with the prickings of the wicked. Therefore, we must take heart and lift up our minds with this hope of salvation, so that we may be ready to devote and surrender ourselves to God, and to follow whatever he commands.

We often see many who are pricked, who, nevertheless, fret and murmur, or else stubbornly strive and struggle, and so, consequently, become furiously mad. Yes, this is the reason they go mad: because they feel such prickings against their will. Therefore, only those people are profitably pricked who are willingly sorrowful and also seek some remedy from God’s hands.