יחזקאל כג:כ פירוש: רש״י

And she lusted for their concubinage [Heb. פִּלַּגְשֵׁיהֶם,] for their concubinage, to be a concubine to them.

those whose flesh is the flesh of donkeys [i.e.,] the phallus.

and...is the issue of horses An expression of a profusion of sexual intercourse, for they engage in sexual intercourse more than any other male animals.