The punishment of flogging can be found in Deuteronomy 25:2–3, a punishment which Jesus also underwent (Matthew 27:26; Mark 15:15; John 19:1). It is not clear if the Sanhedrin used the Roman flagellum nor how many lashes were given to each person1 (though it would have been less than forty, cf. Deuteronomy 25:3). Most likely the flogging was done on the chest and back using a three-stranded strap of calf-hide.2 This punishment would thus have been very painful. It was not a soft option or response. It was a step up from the warning received previously (Acts 4:18).
40 and when they had called in the apostles, they beat them and charged them not to speak in the name of Jesus, and let them go.