Working for a Jewish organization in my day job means I’m finally doing something I’ve wanted to do for a long time: learning more about Jewish holidays. Because both Jewish and Muslim holidays float around the calendar in a way that most Christian and earth-based faith holidays don’t, sometimes curious coincidences happen like today’s confluence of the holiest feast day of the Muslim year, Eid al-Adha, and the much lesser-known Jewish fast day of Tish B’Av, “the saddest day of the Jewish year.”

On Eid al-Adha, as I’ve described before, Muslims dig deep into the Jewish Pentateuch, the oldest parts of the Christian Old Testament, to honor the story of the Prophet Abraham’s sacrifice in the land of Moriah. In respect for the father of all three faiths who was prepared to sacrifice his first son to his singular God, but was instructed at the last moment by the Angel Gabriel to sacrifice a ram instead, Muslims around the world today are slaughtering sheep, goats, cows, camels — whatever their local agriculture and traditions dictate — and sharing the bounty with their less fortunate neighbors. It’s a feast, a family gathering, a three-day celebration of life and love and devotion, and also the culmination of the annual Hajj pilgrimage to Mecca, which all Muslims who are able are expected to do once in their lifetime.

Eid isn’t official until the sighting of the moon the night before, but while Muslims last night were celebrating their founding father, Abraham’s Jewish descendants were beginning at sundown to fast for a day of mourning.

Three tragedies happened to the Jewish people on this day in the Babylonian and Roman eras. On Tish B’Av, the ninth day of the month of Av, in 423 BCE, the Babylonians burned the First Temple in Jerusalem; millions of Jews were killed, and millions more dragged into slavery in Babylon. On Tish B’Av in 70 CE, the rebuilt Second Temple was destroyed by the Romans, but for the holy Western Wall, never to be rebuilt. Thousands of Jews starved to death, and thousands more were sold into slavery.

The site of these tragedies, known today as the Temple Mount, is the hilltop which Jews believe to be the Mount Moriah where Abraham went to sacrifice his son. In Islam, the land of Moriah is the land around Mecca in Saudi Arabia, which is why Hajj ends with a mountaintop sacrifice there.

And on Tish B’Av in 135 CE, the Bar Kochba revolt was crushed by the Romans in Jerusalem.

Also on this day, Jews remember the Spanish Expulsion of 1492, said to have been completed on Tish B’Av, and are encouraged to also honor a long history of other expulsions, slaughters and pogroms that have made victims and refugees of the Jewish people throughout the centuries.

This year, Tish B’Av has particular resonance for many American Jews, who see their own history of danger, destruction and exile playing out on other communities in our own country. This year, in commemoration of Tish B’Av, a coalition of national Jewish organizations organized #ClosetheCamps vigils outside of Immigration and Customs Enforcement (ICE) immigrant detention centers across this country, and in front of the American Embassy in Tel Aviv, Israel.

In the spirit of both Islam and Judaism, and thinking of the unwilling sacrifices of the last week, month and year in this country, I encourage you to take a moment today to reflect with me on sacrifice — intended or imposed upon us — and what history can tell us about resilience and resistance.