Shabbos, 58b: To teach us that even a metal vessel that is merely to 'speak' - to make a noise (such as a bell) needs to be Kashered in fire. ¹

Rashi, Ramban and Targum Yonasan: It means that the vessel must be Kashered in the way that it is used; If the food is heated with hot water and not with fire - such as cups, jugs and bottles, which are only used with hot water, ¹ and which do therefore not absorb ² it must be Kashered in boiling water, whereas if it is heated directly on the fire (Such as a spit-rod and a grille - Rashi [a pot and a kettle ? Rashi in Pesachim, 39a]), ³ then it must be Kashered with fire.

Nazir, 37b: It includes mere taste (that is absorbed in the walls of a K?li) ? that needs to be Kashered (though that is confined to a K?li that was used within twenty-four hours, after which it becaomes ?Nosen Ta?am li?Fegam? and is permitted ? Avodah Zarah, 75b). ¹

Shabbos, 58b: It implies that metal vessels whose basic purpose is to make a noise (such as bells) are subject to Tum?ah. ¹

Avodah Zarah, 75b: To teach us that a utensil that one purchases from a Nochri requires not only Hag'alah, but also Tevilah. ¹

Rashi #1, Rashbam ad Targum Onkelos: It implies that, in addition to being Kashered, the vessel also needs to be sprinkled with water containing ashes of the Parah Adumah.

Rashi #2 (citing the Sifri), Seforno and Targum Yonasan: It implies that, besides Kashering, the vessel requires Tevilah in a Mikveh containing forty Sa'ah - sufficient for a Nidah to immerse in.

Avodah Zarah, 75b and Targum Yonason: It writes "be'Mei Nidah" to teach us that they must be Toveled in a Mikvah of forty Sa'ah, ¹ (and "Vetaher" to teach us that, as opposed to a Nidah, after Tevilah, the vessel does not require Ha'arev Shemesh (waiting until nightfall) before becoming completely Tahor.)

Rashi and Targum Yonasan: It means that vessels that are used only cold, such as cups, jugs and bottles, need only to be Toveled in a Mikvah, if they are made of metal. ¹

Ramban and Moshav Zekenim: It means that vessels that are only used cold must be scrubbed clean in water to remove all remains of Isur from them - and then Toveled.

Avodah Zarah, 75b: To remove the taste that is absorbed in the walls of the vessel (and exudes when it is heated). Consequently, it is confined to vessels that were used hot on the same day - After that, the taste merely spoils the food into which it exudes, and is permitted. ¹

Ramban, Riva and Rosh #1: Because Sichon and Og were kings of the Emori, ¹ one of the seven nations, whose foods - even those that were not Kasher - were permitted, and whose Keilim did not therefore require Kashering ² .

Hadar Zekenim #1: There was a Cherem on what was taken from Sichon and Og. ³

Da'as Zekenim, Hadar Zekenim #2 and Rosh #2: The other wars were in the field, and there were not household Keilim there. Here the war was in Midyan, and they looted the houses, so they needed to warn about absorptions in Keilim.