פירוש על שמות 10:11

לא כן NOT SO as you have said, to take the children with you, but 'לכו נא הגברים ועבדו את ה GO YE WHO ARE ADULT MEN AND SERVE THE LORD.

ועבדו את ה' כי אותה אתם מבקשים, you have requested from me to let you serve the Lord; what do you need women and children for? This is why Pharaoh got angry and expelled Moses and Aaron, adding that “by G’d I will not grant such an unreasonable request!” (verse 10)

This service. . . Rashi is explaining that אותה refers to עבודה , i.e., “go and worship Hashem,” [although the actual word עבודה does not appear in the verse]. אותה cannot refer to the men, for then it should say, “ אותם ”. (Maharshal)