LONDON — A suspect has been arrested after a man was videotaped reading Bible passages to a Jewish man and a boy in the London Underground and accusing them of being “impostors,” in an episode of anti-Semitism that drew outrage.

The British Transport Police said on Saturday that the man, who was not named, was detained on suspicion of having committed a racially aggravated public order offense. Video of the harassment emerged on social media on Friday afternoon, a few hours after the encounter on the Northern Line of London’s subway system.

Video footage posted by another passenger and retweeted more than 18,000 times shows a man reading a section from the Bible to the Jewish man and boy, who are both wearing skullcaps. Witnesses said they were father and son.

The man with the Bible is shown leaning into the boy, quoting Scripture and pointing from the text to the family. The boy stares ahead, looking bewildered, while the man presumed to be his father, one arm wrapped around his son, speaks to him calmly. The man and boy have not been identified.