Mishnayos Eruvin Perek 3 Mishnah 3

נותנו באילן – A person who stands in the public domain and it has in it four handbreadths by handbreadths or more.

למעלה מעשרה אין ערובו ערוב – for since the tree is four [handbreadths] wide, higher than ten [handbreadths], it is the private domain and he acquired his Sabbath camp/place to be the center of Sabbath movements in the public domain and since that if he would want to take his Eruv and eat in it, at the time when the Eruv finds him worthy to do so, which is at twilight, he is not able to take it for he would bring it from the private domain to the public domain, it would not be an Eruv.

למטה מעשרה הרי זה עירוב – for below ten [handbreadths] it is a Karmelit (i.e., an intermediate domain – between a private domain and a public domain, which resembles a public domain – an open area larger than four square handbreadths that is not a public domain, such as fields, rivers, alleyways and lanes), for everything from three until nine [handbreadths] at a width of four [handbreadths] is a Karmelit, and since he took it as his Eruv, there is no prohibition other than Shvut (i.e., the Rabbinic decree to enhance the character of Shabbat as a day of rest), this is an Eruv. But our Mishnah is [according to] Rabbi (i.e., Rabbi Yehuda HaNasi/Judah the Patriarch), who stated that everything that is [done] because of Shvut, they (i.e., the Rabbis) did not decree upon it at twilight. But at the hour when he Eruv is beneficial for him, which is, at twilight, he may take it, and it is found that he and his Eruv are in one place, therefore, it is an Eruv.

נתנו בבור – that is in the Karmelit, such as in the valley or in the fields and it was intended to establish his Sabbath camp in the valley or in the field, it is an Eruv, for the pit itself is the private domain, ad he acquires the Sabbath camp. the center of Sabbath movements in the Karmelit, and at the time when the Eruv benefits hi, that is, at twilight, he can take it, according to Rabbi [Judah the Prince] who stated that everything that is because of Shvut (i.e., to enhance the character of Shabbat as a day of rest), they d not decree upon him at twilight.

אפילו גבוה מאה אמה – but below, there isn’t the width of four [handbreadths] for it is not the private domain, and even though that above it is four [handbreadths] wide, for we require for an Eruv to be on top of a place that has four [handbreadths].

תלוש ונעוץ – it is an Eruv, but if it is attached, it is not an Eruv because, when he takes it, there is a decree lest he cut it off, because the reed is soft and one can make the decree lest he cut it off when he takes it, but a tree is hard, and at twilight, but we don’t suspect lest he will ascend and detach it, but the cutting off of a reed, since it is soft, he will certainly cut it off and will liable because of [the primary category of labor] of reaping. Alternatively, a reed and the tip of a pole are mixed up as attached with something detached, for many reeds are detached and inserted [into the ground] and appear as attached. Because of this, it is necessary to make a decree lest he cut off something attached and think that it is detached, but a tree, one doesn’t make the decree lest one ascend and detached and error to think that it is detached.

נתנו במגדל – of wood.

ואבד המפתח הרי זה ערוב – as, for example, that the lock is tied with cords and ropes, for if he does not finds the key, it is impossible to cut them other than with a knife, the first Tanna/teacher holds, since that it is possible to open it through his cutting the ropes with a knife, there isn’t here a prohibition [that is punishable] through stoning, but rather the prohibition of violating the Rabbinic decree to enhance the character of Shabbat as a day of rest (i.e., Sh’vut), that he damages through the cutting of the ropes but all of those who ruin it are exempt, but the prohibition of Sh’vut (i.e., the Rabbinic decree to enhance the Shabbat as a day of rest) at twilight at the time of his acquisition of the Eruv and they did not make a decree regarding it, as we have stated, therefore, it is an Eruv, for he is able to bring a knife and cut the ropes and take his Eruv. But Rabbi Eliezer holds that a utensil cannot be taken other than for the needs of his usage, and it is prohibited to carry the knife in order to cut the ropes for its use is not other than for cutting foods, and since there are two [prohibitions of Sh’vut], carrying the knife and cutting the ropes, even according to Rabbi [Yehuda Ha-Nasi] who stated that every thing that is because of Sh’vut at twilight, they didn’t not make the decree, in a similar manner, he admits that they made the decree. But the Halakha is not according to Rabbi Eliezer (who holds that the if he doesn’t know that the key is where it belongs, it is not a valid Eruv).