On + date
Incorrect: He was born the 9th of February.
Correct : He was born on the 9th of February.
Note: Generally, a preposition is necessary before a noun indicating the time of an action. But some expressions are not preceded by any preposition. For example:
I went there last year.
I shall visit you next year.
He will be a great philosopher someday.
You can see me any day.
Please give me a ring this afternoon.
