Acts 15:5

But certain believers, [who had been] members of the sect called Pharisees [i.e., a strict sect of the Jewish religion], began saying, "It is necessary to circumcise people [see verse 1] and require them to keep [the ordinances of] the law of Moses."

Acts 15:1

Certain men [i.e., believers, see verse 5] came down from Judea [to Antioch of Syria] and began teaching the brothers this: You cannot be saved unless you are circumcised according to the custom [required] by Moses.

Acts 15:24

We have heard that certain [men] who left here have been upsetting you people and [even] undermining [some people's] spiritual lives by what they have been teaching. This was done without our authorization [or approval].

Acts 21:20

And when they heard [all] this, they gave honor to God, then said to Paul, "Brother, you can see how many thousands of Jewish believers [in Christ] there are [everywhere] and all of them are eager to observe the [requirements of the] law of Moses.

Acts 24:5

We have found this man [i.e., Paul] to be extremely bothersome, and an instigator of strife among the Jews throughout the world and a ringleader of the sect of the Nazarenes.

Acts 26:5-6

They know of my early background; if they were willing to, they could testify that I lived as a [faithful] Pharisee, [which is] the strictest sect of our religion.

Galatians 5:1-3

Christ set us free [from condemnation under the law of Moses], so we could stay free! Remain where you are then, and do not get tangled up again in the enslaving harness [of the law of Moses].

Philippians 3:5-8

[I was] circumcised eight days after I was born; [I am] from the nation of Israelites; from the tribe of Benjamin and of Hebrew ancestry [i.e., an outstanding Hebrew]. As far as the law of Moses is concerned, [I am] a Pharisee [i.e., a strict sect of the Jewish religion].

Treasury of Scripture Knowledge

Summary

But there rose up certain of the sect of the Pharisees which believed, saying, That it was needful to circumcise them, and to command them to keep the law of Moses.

Bible References

That it

Acts 15:1
Certain men [i.e., believers, see verse 5] came down from Judea [to Antioch of Syria] and began teaching the brothers this: You cannot be saved unless you are circumcised according to the custom [required] by Moses.
Galatians 5:1
Christ set us free [from condemnation under the law of Moses], so we could stay free! Remain where you are then, and do not get tangled up again in the enslaving harness [of the law of Moses].