Ein keloheinu is a hymn sung toward the end of Sabbath and holyday morning additional (mussaf) services. In Sephardi and Yemenite traditions it is included in weekday services as well. Its earliest known appearance is in a 9th-century prayerbook (siddur R. Amram Gaon). This is the special tune for High Holy Days (y’dei rashim) in the Portuguese tradition, and it is also a pervasive laḥan (tune) used for other texts in those services, almost as a leitmotif.