Is Tevilas Keilim a Biblical or Rabbinical command?

Some Poskim[1] rule that the Mitzvah of Tevilas Keilim, immersing vessels, is a Biblical obligation.[2] Other Poskim[3] rule the Mitzvah of immersing vessels is a Rabbinical obligation.[4] Practically, we rule like the former opinion, that Tevilas Keilim is a Biblical obligation.[5] Nevertheless, this only applies to vessels made of metal, however vessels made of glass and other materials that require immersion, according to all opinions is only Rabbinically obligated.[6] [There are various practical ramifications regarding whether one views the Mitzvah as Biblical or Rabbinical, such as; 1) Immersing a vessel on Shabbos[7]; 2) Trusting a child to immerse.[8]]

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[1] Stam opinion in Admur 159/21; 2^nd opinion in Admur 323/8; Implication of Michaber 320/9 and 14 and 17 who rules a Katan is not believed; Taz 120/16; Peri Chadash 120/1 [see there in length]; Rashba in Teshuvah; Raavad; Ramban; Rashi Avoda Zara 75b; Tosafus Avoda Zara ibid; Rabbeinu Tam Yuma 78; Semak 199; Issur Viheter 58/91

[2] The source: This is learned from the verse “Davar Asher Yavo Baeish Taaviru Baeish Vetaher.” The word “Vetaher” teaches us that the verssel must be immersed.

[3] 1^st opinion in Admur 323/8; Rambam Machalos Assuros 17/5, as understood by Rashba in Toras Habayis p. 155 and Peri Chadash ibid [however see Rashba in Teshuvah ibid and Aruch Hashulchan 120/1-3 for alternative understanding in Rambam]; Ran; Ritva; Or Zarua 1/359; Radbaz 34 that so rule majority of Poskim; Yeshuos Yaakov O.C. 509/4

[4] The reason: As the above verse is in truth referring to Kashering the vessel from non-Kosher foods, and it is regarding this Kashering that the verse concludes “Vitaher” and it becomes pure. Nonetheless, being that the verse hints to purification, which usually refers to immersion in a Mikveh, therefore the Sages decreed that one is to immerse the vessel, and the above verse is a Asmachta/support for this decree. [Rambam ibid, explained in Peri Chadash ibid]

[5] Admur 159/21; 323/8 “The main opinion follows that Tevilas Keilim is Biblical, as explained in Yoreh Deah ibid”; Aruch Hashulchan 120/4 that so agree majority of Poskim

[6] Peri Chadash 120/3; Chochmas Adam 73/19, brought in Pischeiy Teshuvah 120/3; Aruch Hashulchan 120/24; Rashi, brought in Aruch Hashulchan 120/1 “Specifically metal”; See Taz 120/1 “It is only common to use for a meal vessels made of metal.”

[7] See Admur 323/8

[8] See Michaber 120/14