From Mark Cohen’s Under Crescent & Cross: The Jews in the Middle Ages:
An aspect of Jewish-gentile sociability under Islam that seems to lack a counterpart in the Jewish-Christian world is the world of shared popular religious practices… particularly in the joint worship of saints. Here, interdenominational religiosity has its basis in the fact that the Qur’an honors biblical figures as prophets. Their grave sites attracted both Muslims and Jews….
Two famous European Jewish travelers of the twelfth century, Benjamin of Tudela and Petaḥiah of Regensburg, noted this interfaith phenomenon with amazement, so uncharacteristic was it of the Christian milieu from which they hailed (Christian Spain and Germany, respectively). Benjamin found Muslims and Jews sharing in the veneration of Ezekiel, the biblical prophet of the Babylonian Exile, at the site of his tomb and at the synagogue named after him, which was tended by Muslim and Jewish keepers.
People come from a distance to pray there from the time of the New Year until the Day of Atonement. The Jews have great rejoicings on these occasions. Thither also come the Head of the Diaspora and the Heads of the Academies from Baghdad. Their camp occupies a space of about two miles, and Arab merchants come there as well…. Distinguished Muslims also come there to pray, so great is their love for Ezekiel the Prophet.
The Jews maintained a synagogue at the sepulcher of Ezra. “And at the side thereof the Muslims erected a house of prayer out of their great love and veneration for him, and they like the Jews on that account.”
Petaḥiah, who made his journey shortly after Benjamin, obtained from the head of the yeshiva in Baghdad a document instructing Jews to conduct him to grave sites of Jewish scholars and righteous men (tzaddiqim). The first place he visited was the grave of Ezekiel. Petaḥiah relates: “On the holiday of Sukkot, people come there from all lands… about sixty or eighty thousand Jews, in addition to Muslims.” Huts (sukkot) were erected in the courtyard of the prophet’s tomb, and people made vows and gave donations in hopes of gaining a favor. Petaḥiah heard a story about a Muslim notable (sar) who vowed that if his barren mare bore na offspring, he would give the foal to Ezekiel.
[E]very Muslim who goes to the place of Muhammad [i.e., on the pilgrimage to Mecca and Medina], travels via the grave of Ezekiel, where he gives a gift and a donation to Ezekiel and vows in prayer: “Our lord Ezekiel, if I return I shall give you such-and such.”
Muslims even made donations and prayed at the tomb of the Mishnaic sage Rabbi Meir and bowed in prayer at the burial site of Ezra the Scribe.
In the late fifteenth century, the Italian Jewish traveler Meshullam of Volterra gazed in wonderment at the phenomenon of Jewish-Muslim popular religion. Like his two twelfth-century precursors, Meshullam hailed from a Christian environment where Jews and Christians were mutually repelled by each other’s religion. Meshullam could only find this kind of interaction between Jews and gentiles astonishing.
– Mark R. Cohen, Under Crescent & Cross: The Jews in the Middle Ages, 135-136