שמות ח:כב פירוש: רש״י, רשב״ם, טור הארוך וSiftei Chakhamim

תועבת מצרים THE ABOMINATION OF THE EGYPTIANS — This means: that which the Egyptians reverence (their idol), just as, (2 Kings 23:13) “and for Milcom the abomination (תועבת) of the children of Ammon”, but in relation to the Israelites it (Scripture) calls it תועבה. We may explain these words in another sense also: תועבת מצרים — The act of sacrifice which we practise is a hateful thing to the Egyptians seing that we sacrifice their god (sheep which were reverenced as gods in Egypt).

כי תועבת מצרים, sheep were something despicable in the eyes of the Egyptians.

כי תועבת מצרים, “for it is an abomination in the eyes of the Egyptians;” some commentators claim that this line is a comment added to the Torah by Moses, seeing he wanted to take a swipe at idolatry. When confronting Pharaoh in person, Moses referred to their deities as אלוהי מצרים, and not as תועבה. The reason Moses was provoked to refer to the Egyptians’ deities by a derogatory term was that they worshipped the image of a lamb.