Acts 21:25-26

25But with regard to the Gentiles who have believed [in Christ], we have sent them a letter with our decision that they should abstain from meat sacrificed to idols and from [consuming] blood and from [the meat of] what has been strangled and from sexual immorality.”

26Then Paul took the [four] men, and the next day he purified himself along with them [by submitting to the ritual]. He went into the temple to give notice of [the time] when the days of purification [ending each vow] would be fulfilled and the usual offering could be presented on behalf of each one.