Ramban: Because a. whereas there the Torah discusses an animal that strays from the path ("To'eh ba'Derech") - where one merely needs to return it to the path, here it adds that if it has wandered far from the path ("Nidachim"), one must return it, and b. Whereas there the Torah refers to an ox or a donkey that is lost, here it adds a lamb, which is considered totally lost. ¹

Bava Metzi'a, 33a and Sifri: The Chachamim therefore explained Re'iyah which includes Pegiyah - a distance of one Ris (a seven and a halfth of a Mil = a hundred and sixty-seven and two-thirds Amos).

Oznayim la'Torah: After teaching us in Mishpatim, the Mitzvah of overcoming one's Yeitzer ha'Ra and returning the lost article of one's enemy, the Torah refers here to the ox of one's brother to teach us returning a lost article, is a Mitzvah in and of itself and that the Torahmentions "Shor Oyivcha" in Mishpatim to give precedence to the ox of one's enemy over that of one's friend.

Bava Metzi'a, 27a: It mentions "Shor" to include the shearings on its tail and "Seh" to include its wool ¹ in the Don of Hasavas Aveidah.

Sifri: It implies that one is only Chayav to return the animal if it is obviously lost - a cow with its accessories all awry or running in the vine-yard among the vines, ¹ but not if it is grazing by the roadside.

Rashi #1, Targum Onkelos and Targum Yonasan: It implies that one may not hide one's eyes from a lost article - to pretend that one did not see it.

Rashi #2 (citing the Sifri): It implies that sometimes one may or must ignore it.

Bava Metzi'a, 30a: The Torah writes "Vehis'alamta meihem" (positive) ¹ , implying that one is sometimes permitted to hide one's eyes from a lost article - 1. if he is a Kohen and it is in a Beis-ha'Kevaros; 2. if he is an elder and it would be below his dignity to return it ² and 3. if his loss of work exceeds the value of the article.

Bava Metzi'a, 26b: 'If Reuven sees a Sela falling from Shimon ? if he picks it up a. ? before Yi'ush (Shimon has given-up on finding it) with the intention of stealing it ¹ he transgresses "Lo Sigzol", "Hashev Teshivem" and "Lo Suchal Lehis'alem"; b. ? before Yi'ush with the intention of returning it, and then he decides to keep it, he transgresses (only) "Hashev Teshivem"; c. ? after Yi'ush (even in order to return it) he transgresses (only) "Lo Suchal Lehis'alem".

Bava Metzi'a, 30b: "Hashev" implies even four or five times, ² and the Torah adds "Teshivem", since that is the way people speak.

Bava Metzi'a, 31a: To teach us that one may return the article to the owner's garden or his wood-storage area ³ - to teach us that one may return the lost article even without the owner's knowledge. ⁴

Sifri: To tech us that he must return the lost article into the owner's domain - to a location where the owner will see it and look after it. ¹ Otherwise, he will be liable if it gets lost again,