How, then, is "horses" to be understood? As "idle" horses.
Whence is it derived that the addition of even one idle horse constitutes a transgression? From (Ibid.) "in order to multiply a horse."
Now does this not follow a fortiori, viz.: If a mitzvah on which the covenant hinges (i.e., to go to Eretz Yisrael and not to return to Egypt [viz. Shemoth 14:12]) — a transgression (in this instance, returning there for horses,) returns them to Egypt, (this, the thrust of "that he not return the people to Egypt in order to add a horse"), then (returning them to the) other lands, on which the covenant does not hinge, how much more so (will a transgression return them there)!