From the filthiness of the heathen, i.e. such as had forsaken that filthy and idolatrous religion of the heathens, and were proselyted to the Jewish religion; for such were allowed to eat the passover, Exodus 12:48 Numbers 9:14.
Related Commentaries of Ezra 6:21
Ezra 6:21
21 And the children of Israel, which were come again out of captivity, and all such as had separated themselves unto them from the filthiness of the heathen of the land, to seek the LORD God of Israel, did eat,