1987, Salzberg, Joel, Critical Essays on Bernard Malamud, G. K. Hall, ISBN9780816188819, page 219:
But Cohn can and does extend "recognition," suspecting from the beginning a significant core of feeling in the immense isolato, seeing hints of a "true gentleman" and even going so far as to offer him the Elijah seat at the Seder.
Because of my schedule of chores, the seder was half-over when I arrived and there was a choice of two seats: one right beside the rabbi, or else Elijah's seat, a chair that sits empty in case the prophet Elijah turns up with the Messiah in tow, on his donkey. I sat beside Michael as I am not Elijah, and I have absolutely no messianic pretensions or connections, and thus the Elijah seat implied responsibilities that I did not care to take on.
2004, Koén-Sarano, Matilda, King Solomon and the Golden Fish: Tales from the Sephardic Tradition, Wayne State University Press, page 193:
The Elijah seat on which the sandák sits and the performance of the brit at the synagogue as a religious ritual are elements that help affirm the link to Judaism.
(by extension) seat formally reserved for an absent special guest
2012 August 31, Beaujon, Andrew, “Empty-chair interviews officially a trend after Clint Eastwood RNC speech”, in Poynter:
More important, this was the fourth incidence of an Elijah seat on TV since the beginning of the year.