Following the game at Stamford Bridge last month which saw Gabriel shown a red card, then have that red card rescinded, then get banned for improper conduct, the FA have announced that they have fined the club for breach of conduct rules.
In a statement on their website, they say:
Following an Independent Regulatory Commission hearing, Chelsea and Arsenal have been fined £40,000 and £30,000 respectively and warned as to their future conduct after both clubs admitted a breach of FA Rule E20.
The charge was for failing to ensure their players conducted themselves in an orderly fashion from the 44th to the 47th minute of the game at Stamford Bridge on 19 September 2015.
The Independent Regulatory Commission considered the previous disciplinary records of both clubs in reaching its decision on sanction.