Leviticus 23:21

And ye shall proclaim on the selfsame day, [that] it may be an holy convocation unto you,.... This proclamation was made by the priests with the sound of a trumpet, that the people might observe that this fiftieth day, or day of Pentecost, was devoted to sacred service, and that they were called to holy exercises in it:ye shall do no servile work [therein]; what was not necessary for food, as Ben Gersom observes, but what was necessary on that account, as kindling a fire, &c.