Rashi on Exodus 11:9/רש"י על שמות י״א:ט׳

1למען רבות מופתי SO THAT MY WONDERS MAY BE MULTIPLIED (more lit., so that my wonders may be many) — referring not to one wonder alone (the slaying of the firstborn) but to the slaying of the firstborn, the division of the Red Sea and the overthrowing of the Egyptians in it.