When they heard this, they were furious and wanted to put them to death. But a Pharisee named Gamaliel, a teacher of the law, who was honored by all the people, stood up in the Sanhedrin and ordered that the men be put outside for a little while. Then he addressed them: "Men of Israel, consider carefully what you intend to do to these men. Some time ago Theudas appeared, claiming to be somebody, and about four hundred men rallied to him. He was killed, all his followers were dispersed, and it all came to nothing. After him, Judas the Galilean appeared in the days of the census and led a band of people in revolt. He too was killed, and all his followers were scattered. Therefore, in the present case I advise you: Leave these men alone! Let them go! For if their purpose or activity is of human origin, it will fail. But if it is from God, you will not be able to stop these men; you will only find yourselves fighting against God."Pretty smart stuff, but who is this guy? Besides the Bible, Jewish writings include two other books: the Talmud and the Mishna, both of which are commentaries on the Bible and records of the wisdom of prominent Hebrew rabbis of the ages. (Actually, there are two Talmuds and the Mishna is more of a compilation, but you get the idea.) In both, Gamaliel is noted as a wise man, a prominent and powerful teacher, and the author of many law books of his own. We are also going to learn in Acts 22:3 that Gamaliel was the main teacher and mentor of Saul, before his conversion and taking of the name of Paul.
His speech persuaded them.
Acts 5:33-40
Essentially, Gamaliel was one of the foremost experts in the Jewish Law and a professor of law who molded many rabbis and pharisees of the next generation. It is no accident that he is quoted here by name. The readers of Luke's book of Acts would have known Gamaliel at least as well as we know the name of Billy Graham or Josh McDowell. Maybe even as well as we know the name Albert Einstein.