The incident happened in the visitors dugout shortly before Saturday night's game between the Yankees and the Kansas City Royals. Rivera, who was conducting an interview with a small group of reporters about his meeting earlier in the day with the family of a young boy killed in an airport accident, asked Chamberlain to lower his voice because he could not hear the questions being asked.
"Joba, yo, bro, bro,'' Rivera could be heard saying to Chamberlain on a tape of the interview played for ESPNNewYork.com.
"Suave,'' Rivera said, using the Spanish word for soft, while making a palms-down gesture with his hands, according to eyewitnesses.
"You do this every day,'' replied Chamberlain, who apparently was trying to talk to some family members in the stands near the Yankees dugout at the time. "I don't see my family every day.''
Rivera could be heard chuckling on the tape, and continued the interview. But afterward, he was approached by Chamberlain, who said, "Don't ever shush me again.''
According to witnesses, Rivera tried to laugh that off, too, but a stony-faced Chamberlain repeated, in tones that contained a hint of threat, "No, seriously. Don't ever shush me again.''