Why do the Makos follow a set pattern? In the first out of each set of three Makos, Moshe confronted Pharaoh at the Nile; in the second, at the palace; whereas the third had no warning at all?
Refer to 7:14:8:2, regarding the Makos' breakup into the categories De'tzach, A'dash, Be'achav. 1
Our Pasuk says only, "Arise early in the morning, and stand (Hisyatzev) before Pharaoh;" it does not state explicitly the venue for this confrontation should be at the Nile. Nevertheless, Maharal (Gevuros Hashem, beg. Ch. 57, p. 251) understands it as such. (The Ibn Ezra is unsure of this; also see Shemos Rabah 12:1; and refer to 9:13:2).
When commanding Moshe to confront Pharaoh, why did Hashem not add "Hinei Yotzei ha'Maymah," like He did by the plague of frogs?
Oznayim la'Torah: Because Pharaoh's boils had not yet had a chance to heal, and a person with boils is not able to bathe.
