ACT 21:24

24 Go with these men [to the Temple] and [ritually] purify yourself along with them. Then, [when it is time for them to offer the sacrifices for that ritual], pay for what they offer [as sacrifices]. After that, they can shave their heads [to show that they have done what they promised to do. And when people see you in the courts of the Temple with those men], they will know that what they have been told {what people have told them} about you is not true. Instead, all of them will know that you obey all our Jewish laws [and rituals].