Why does the Torah write that Aharon's staff swallowed those of the magicians and not that the snake swallowed their snakes?
Rashi: Because it was only after all the snakes turned back into staffs that Aharon's staff swallowed theirs. 1
Rashi (in Shabbos, 97a): 'A miracle within a miracle': Hadar Zekenim: Also, it did not become thicker after swallowing them (It is not clear how the Hadar Zekenim knows that)? Par'oh was afraid that it would also swallow him and his throne!
Presumably, the Pasuk refers to the staff of Aharon, because strictly speaking, it was not the snake that belonged to Aharon but the staff - turned snake.
Why did the fact that Aharon's staff swallowed their staffs not convince the astrologers of Hashem's superiority?
Oznayim la'Torah: Because they could argue that, had they known that Aharon would command his staff to swallow their staffs, they would have commanded their staffs to swallow his