Rashi on Exodus 5:3/רש"י על שמות ה׳:ג׳

1פן יפגענו LEST HE LIGHT ON US — They should have said, “Lest He light on thee (Pharaoh) [with pestilence] etc.” — but they showed respect to royalty (the king) by thus expressing themselves. This term פגיעה “lighting on”, “meeting” denotes meeting with death (Exodus Rabbah 5:15).