The Canadiens forward blindsided Stepan with a late shoulder hit, leaving him lying face down on the ice about three minutes into Thursday's game. There was no penalty on the play and Stepan returned to the ice later in the period after going to the dressing room.
"We looked at it," Rangers coach Alain Vigneault said of the hit. "The referees missed it."
Montreal won 3-2 in overtime to cut New York's lead in the series to two games to one.
The Prust hearing was announced on Twitter by the NHL department of player safety.