The is a widespread wedding custom to sing a short benediction, מי אדיר, when the groom arrives under the canopy, and to sing מי בן שיח, for the bride as she arrives and walks around the groom.
The Kitzur Shulkhan Arukh mentions singing according to the custom of the place, and I understand why it would be fitting to sing such things in particular at the ceremony, but where do these passages come from?
