"You never ******* saw that."
Kathleen Walker is also said to have told a colleague: "That was not really a slap" or words to that effect, during the incident at Applecross Nursing Home.
The staff nurse is facing five charges of misconduct at the family-run care home in Barrhead, East Renfrewshire. The alleged assault is said to have happened during the night shift of November 1, 2012.
The home notified the Care Inspectorate, social services and the police and launched its own probe.
Ms Walker, who was later sacked by the home, is also alleged to have failed to call an ambulance after a patient was found lying on the floor with a facial injury. The charge states that she failed to contact NHS 24 or refer the patient to hospital, failed to carry out any observational checks and failed to record the incident.
The home cares for up to 68 residents, with referrals from Glasgow City Council.
A council spokesman said: "It would be inappropriate to comment ahead of any hearing. Personnel issues at the home are a matter for the operator to discuss."