Eruvin, Chapter 10, Mishnah 11. This mishnah, and the ones that follow it, deal with cases in which we permit in the Beis HaMikdash things that are forbidden by rabbinic decree. The discussion in each mishnah will therefore center on the question of which things are forbidden only rabbinically - and those we are allowed to permit in the Mikdash - and which things are forbidden by Torah law, and are therefore forbidden even in the Beis HaMikdash.
We already opened this discussion in the previous mishnah, regarding the neger. The neger is a bolt used to lock a door. Sometimes the locking was done by inserting the bolt into a hole in the ground, and that may constitute the forbidden labor of building - after all, closing a door in a permanent manner falls under the category of building.
"Neger hanigrar":
Our mishnah discusses the neger hanigrar. Although the two words sound alike, they are two different terms: neger - a bolt, and hanigrar - which drags along the ground. As we mentioned in the previous mishnah, the bolt has to be tied and hanging on the door, so that it should be evident that it is not a permanent part of the building but rather a utensil used for inserting and removing, functioning as a lock.
But what is the ruling when the bolt is tied to the door yet does not hang, but rather drags along the floor? In such a case the mishnah rules that one may lock with it in the Mikdash: since it is still evident that this is not actual building, there is nothing here but a rabbinic prohibition, and therefore one may use it to lock the door in the Beis HaMikdash. "Aval lo bamedinah" - outside the Beis HaMikdash, in the rest of Eretz Yisrael, the rabbinic prohibition remains in force.
"Vehamunach kan vechan asur" - a bolt that is not attached to the door at all but is merely resting there may not be used to lock the door, neither outside the Mikdash nor in the Beis HaMikdash. That is, there is a Torah prohibition here, since this is actual building, and therefore we have no power to permit it even in the Beis HaMikdash. This is the opinion of the first Tanna.
The view of Rabbi Yehudah:
"Hamunach" - a bolt that rests on the ground and is not attached to the door at all involves only a rabbinic prohibition, and it is therefore permitted in the Mikdash.
"Vehanigrar" - a bolt that is tied to the door and drags along the floor is permitted even outside the Mikdash. In Rabbi Yehudah's view there is no need for it to be hanging; it is enough that it be attached to the door, even if it drags along the floor.
In summary: the first Tanna and Rabbi Yehudah disagree about both situations of the bolt. According to the first Tanna, the one that drags is permitted in the Mikdash and forbidden outside it, while the one that merely rests is forbidden in both places because its prohibition is from the Torah. According to Rabbi Yehudah, the one that rests is permitted in the Mikdash, and the one that drags is permitted even outside it.