(Ibid. 3) "Forty shall he smite him": I might think "forty," literally; it is, therefore, written "in number. Forty" — a number that is close to forty (i.e., thirty-nine). R. Yehudah says: Forty, literally. And where is he smitten (the other two-thirds)? Between his shoulders. "shall he smite him": and not the ground (together with him).
"shall he smite him": and not his garment. "shall he smite him": Two are not smitten as one.
"and not more": If he does smite more, he transgresses a negative commandment. This tells me only of his going beyond the Torah's number (i.e., thirty-nine). Whence do we derive (the same for his going beyond) the court's assessment (of how many he can bear)? From "and not more. Lest he smite him more" — in any event.