sermon

noun
1
a talk on a moral or religious subject, usually given by a religious leader during a service
موعظه, خطبه, خطابه, سخنرانی مذهبی, وعظ
2
moral advice that a person tries to give you in a long talk
موعظه, نصیحت
We had to listen to a long sermon on the evils of wasting time.