In his later years, the מגיד מדובנא was a רב in a shul where he and the חזן didn’t get along. Accordingly, the מגיד refused to pray in that shul, except when his contract required him to do so, including on הושענא רבה. One person observed that all year למנצח and מזמור לתודה are not said together. On the שבת when we say למנצח, we don’t say מזמור לתודה and on weekdays when we say מזמור לתודה, we don’t say למנצח. It’s only on הושענא רבה that they meet, when we say both למנצח and מזמור לתודה and so it is with the מגיד and the חזן.

05/07/2020