פירוש על עבודה זרה 72:10

The two rabbis here attribute the prohibition of sex with a non-Jewish woman to the Hasmoneans, who lived about 150 years before Shammai and Hillel. These rabbis use some strong rhetoric with regard to this prohibition, making it akin to several grave sins. The difference between the two is only with regard to the last one. R. Dimi says it is as if she is married. Ravin says it is as if she is a “zonah” which technically is a woman prohibited to a priest.