improved error message

Author: arw2019

pandas/_libs/tslibs/parsing.pyx

@@ -161,16 +161,16 @@ cdef inline object _parse_delimited_date(str date_string, bint dayfirst):
             # in C api, thus we call faster C version for 3.6.1 or newer
 
             if dayfirst and not swapped_day_and_month:
-                warnings.warn(f"Parsing {date_string} MM/DD format.")
+                warnings.warn(f"Parsing '{date_string}' in MM/DD/YYYY format.")
             elif not dayfirst and swapped_day_and_month:
-                warnings.warn(f"Parsing {date_string} DD/MM format.")
+                warnings.warn(f"Parsing '{date_string}' in DD/MM/YYYY format.")
 
             return datetime_new(year, month, day, 0, 0, 0, 0, None), reso
 
         if dayfirst and not swapped_day_and_month:
-            warnings.warn(f"Parsing {date_string} MM/DD format.")
+            warnings.warn(f"Parsing '{date_string}' in MM/DD/YYYY format.")
         elif not dayfirst and swapped_day_and_month:
-            warnings.warn(f"Parsing {date_string} DD/MM format.")
+            warnings.warn(f"Parsing '{date_string}' in DD/MM/YYYY format.")
 
         return datetime(year, month, day, 0, 0, 0, 0, None), reso