Hi Farha Saleem,
You can open the properties dialog in Enterprise Manager and click "Permissions..."
or, you can do it with a query (you'll have to add the schema portion if you need that)...
SELECT su.name, -- user name with permission
so.name -- procedure name
FROM syspermissions AS sp
INNER JOIN sysobjects AS so
ON sp.id = so.id
INNER JOIN sysusers AS su
ON sp.grantee = su.uid
WHERE so.name = 'procedure_name'