Application for sick leave

The Principal,
Govt. High School,
City A. B. C.
Sir,
Most respectfully I beg to say that I am suffering from fever since last evening. I also feel great pain in body. My doctor has advised me a complete rest for three days. Kindly grant me leave for three days. The madical certificate is attached with the application. I shall be very thankful to you for that.
Yours obediently,
Name X. Y. Z.