Albert Barnes Commentary Acts 5:40

"And to him they agreed: and when they had called the apostles unto them, they beat them and charged them not to speak in the name of Jesus, and let them go." — Acts 5:40 (ASV)

And to him they agreed. In Greek, they were persuaded by him, or they trusted him. They agreed only as far as their design of putting them to death was concerned. They abandoned that design. But they did not comply with his advice to leave them entirely alone.

And beaten them. The usual number of lashes inflicted on offenders was thirty-nine (2 Corinthians 11:24). Beating, or whipping, was a common method of punishing minor offenses among the Jews. It was expressly foretold by the Savior that the apostles would be subjected to this (Matthew 10:17). The reason why they did not adopt Gamaliel's advice altogether, doubtless was, that if they did, they feared their authority would be despised by the people.

They had commanded them not to preach; they had threatened them (Acts 4:18; Acts 5:28); they had imprisoned them (Acts 5:18); and now, if they allowed them to go without even the appearance of punishment, their authority, they feared, would be despised by the nation, and it would be supposed that the apostles had triumphed over the Sanhedrin.

It is probable, also, that they were so indignant that they could not allow them to go without the gratification of subjecting them to the public odium of a whipping. People, if they cannot accomplish their full purposes of malignity against the gospel, will content themselves with even some petty annoyance and malignity, rather than leave it alone.