Av HaRachamim

Av Harachamim or Abh Haraḥamim ( "Father [of] mercy" or "Merciful Father") is a Jewish memorial prayer which was written in the late eleventh or early twelfth century, after the destruction of the Ashkenazi communities around the Rhine River by Christian crusaders during the First Crusade. First appearing in prayer books in 1290, it is printed in every Orthodox siddur in the European traditions of Nusach Sefarad and Nusach Ashkenaz and recited as part of the weekly Shabbat services, or in some communities on the Shabbat before Shavuot and Tisha B'Av.

The Yizkor service on Jewish holidays concludes with the Av Harachamim, which prays for the souls of all Jewish martyrs.