The evidence for the allegation came from one witness, Ramires. Ramires, whose first language is not English, explained that his instinctive reaction was to seek confirmation from John Obi Mikel as to what the referee had said.
John Obi Mikel, who was being spoken to by the referee, was much closer to the referee than Ramires and did not hear what it is suggested was said to him.
Three other witnesses, i.e. the other Match Officials, to whom everything said by referee was relayed via their communication equipment, are adamant the alleged words were not uttered.
There is nothing in the video footage to support the allegation.
For completeness, but of lesser weight, two other players, whose first language is English and were in the vicinity, did not hear anything untoward.