Use Custom Formula Field to get Weekday from a Date but as a String

Use Custom Formula Field to get Weekday from a Date but as a String

Can someone please help: I need to Create a Custom Formula Field to get the Weekday  from a DateTime  Custom Field: AppoitmentDate 

BUT as a String, in ex: 'Sunday'  not as a number '1.0' as the 'Weekday' function already returns it

I've tried with nested IFs as in this formula but i a get a 'Syntax error for the given formula' 

if(Weekday(${Leads.ApointmentDate})=1,'Sunday',if(Weekday(${Leads.ApointmentDate})=2,'Monday',if(Weekday(${Leads.ApointmentDate})=3,'Tuesday', if(Weekday(${Leads.ApointmentDate})=4,'Wednesday', if(Weekday(${Leads.ApointmentDate})=5,'Tuesday', if(Weekday(${Leads.ApointmentDate})=6,'Friday', if(Weekday(${Leads.ApointmentDate})=7,'Saturday','')))))))

Any help would be highly appreciated, Thanks!