שמות כב, ל: וְאַנְשֵׁי־קֹדֶשׁ תִהְיוּן לִי וּבָשָר בַשָדֶה טְרֵפָה לֹא תֹאכֵלוּ לַכֶלֶב תַשְׁלִכוּן אֹתוֹ:
“Throw it (the tereifah) to the dog”
The final nun of the word תשלכון is not grammatically necessary. This extra letter teaches that a carcass should be removed 50 amos (letter nun = 50) from a town (in order to diminish the effects of its foul smell.
The Baal haTurim indicates that the word תשלכון can be read as תשלכו ן' one should throw it fifty.
(The Gemara in Shabbos 155b states that one should throw the scraps of meat and bone to a stray dog only in the Midbar. However, in the city one should give nothing to the dog, because it could become a great pest, always coming back. Thus, in the city one must place the tereifah meat in the garbage heap, but it must be at least 50 amos from the city.)
