Bava Kamma, Chapter 5, Mishnah 7. In this Mishnah we conclude the topic of a pit. The verse used the language "and an ox or a donkey falls in there" - that if an ox or a donkey fell into the pit, the one responsible for the pit is obligated to pay for the damage. The point of our Mishnah is to establish that even though the verse mentioned an ox and a donkey, there is nothing unique about these types of animals: even if a pet dog or any other creature fell into his fellow's pit, the owner of the pit is liable for the damage payments caused to the animal.
Since the Mishnah deals with this point, it continues and establishes that the same rule applies in many matters in the Chumash. It does not list all of them, but rather many of them.
The cases listed by the Mishnah:
"Echad shor v'echad kol behemah linefilas habor" - regarding falling into a pit there is no difference between an ox and any other type of animal, and the one responsible for the pit is liable for damages.
"Ulehafrashas Har Sinai" - the distancing from Mount Sinai. It is stated: "Beware of ascending the mountain and touching its edge" - a warning not to ascend the mountain and not even to touch its edge, and later: "whether animal or man, it shall not live." One might have thought that this refers specifically to behemos, which are domesticated farm animals, but this is not the case: even a person who left Egypt with his pet giraffe - it too would be punished to the same extent if it got too close to the mountain. While it is not entirely clear why the Mishnah needed to reference a one-time event that happened at Mount Sinai, the Mishnah does sometimes take this approach.
"Uletashlumei kefel" - concerning theft, the verse says: "If the theft shall be found in his hand, from an ox to a donkey to a sheep, alive - he shall pay double." The thief returns the stolen animal and pays its value again. Even though the verse specified certain animals, the rule applies to all types of animals.
"Ulehashavas aveidah" - it is stated in the Book of Devarim: "You shall not see your brother's ox or his sheep straying and hide yourself from them, you shall surely return them to your brother," and also: "and so shall you do to his donkey." There is nothing unique about these animals: one who sees his fellow's anteater wandering and lost - he is also obligated to return it.
"Lifrikah" - the mitzvah to assist in unloading a burden from an animal. It is stated: "When you see the donkey of your enemy lying under its burden, and you might refrain from helping him - you shall surely help him." One who sees the donkey lying and being crushed under the weight of its burden is not permitted to refrain from intervening, but rather he must assist in unloading it together with its owner, so that it will not be crushed. And even though the verse specified a donkey, the same rule also applies to one who loaded a burden onto his battle elephant.
"Lachasimah" - placing a muzzle on an animal's mouth. The verse states explicitly: "You shall not muzzle an ox in its threshing" - an ox threshing in the granary, one may not muzzle its mouth, but rather one must allow it to eat while performing its work. But there is nothing unique about an ox: one who performs other work in grain with a different type of animal is forbidden to muzzle it.
"Lekilayim" - in the laws of kilayim with animals there are two applications that are unrelated to each other:
Crossbreeding species - "You shall not mate your animal with a different species," such as mating a horse with a donkey in order to create a mule. This prohibition applies not only to behemos, which are domesticated farm animals, but also to wild animals.
Plowing - "You shall not plow with an ox and a donkey together." One may not plow with two animals harnessed together and pulling the plow, an ox and a donkey, and the same rule applies to any animals of two different species.
"Uleshabbos" - the verse that we say in Kiddush: "You shall not do any work, you, and your son, and your daughter... and your ox, and your donkey, and all your animals." Here too the rule is not limited to an ox and a donkey: someone who owns a pet giraffe is forbidden to work it on Shabbos.
It is interesting that the Rambam learns, and the Bartenura cites this, that the prohibition on a Torah level - at least in the part of plowing - is specifically when the two animals are one tamei species and one tahor species, one kosher and one that is not kosher. According to this, two tamei animals pulling together, or two tahor animals, involve only a rabbinic prohibition. Others, such as the Rosh, learned that the prohibition applies on a Torah level even with two animals that are wild animals or both domesticated animals, kosher or non-kosher. There are, of course, practical differences regarding this, but the common point is that even though the verse speaks of specific animals like an ox and a donkey, its intention is to animals in general.
The Mishnah adds: "Vechen chayah va'of kayotzei bahen" - the matters are not stated only regarding domesticated farm animals, but even regarding a chayah, which is a wild animal, and a bird. Even an ostrich and the like are included in all of these laws equally to the laws of domesticated animals.
If so, the Mishnah asks: "Lammah ne'emar shor o chamor?" - why did the verse specify regarding the law of a pit specifically an ox or a donkey? And its answer: "Ella shediber hakasuv bohoveh" - the verse stated the regular and common cases, since it is the way of people to keep oxen and donkeys. However, the law applies today equally to dogs and cats, which are much more common.
In summary: In this Mishnah we learned that even though the verse used specific animals, there is no uniqueness in their types, and the law applies to all animals - regarding falling into a pit, distancing from Mount Sinai, double payments, returning a lost object, unloading, muzzling, kilayim, and Shabbos, and similarly with a wild animal and a bird. The principle that arises from here is: "The verse spoke of the present reality."