פירוש על עבודה זרה 11:4

If the Torah had just written “with you” I would not have known that Noah had to bring fertile animals on to the ark. I might have thought that they were just there for company. He could not have brought a trefa but he could have brought an old or infertile animal. Therefore, the Torah says that the animal must be able to bear children (seed).

Ishmael prohibits engaging in business for the three days before and the three days following the festival. From his phrasing it seems that the festival day is not included, for if it was, it would be included twice—with the days before and with the days following.
The Talmud rejects this answer. It might be that R. Ishmael does include the festival day with the three days. It is prohibited to engage in business for three days before, including the festival. The phrase “three days following” is not precise, and does include the festival day. He only used this language to parallel the phrase “three preceding.”