R. Yishmael says: You say this, but perhaps the intent is (literally) to distinguish between day and night, viz.: If he killed him in the daytime, he is liable; if at night, he is not liable. It is, therefore, written (Devarim 22:26) "and to the maiden you shall do nothing; for as a man would rise up against his neighbor and murder him, so, is this thing" (raping a maiden).