There are those who say that Rabbi Yoḥanan says in the name of Rabbi Shimon bar Yoḥai: From where in the Torah is there a hint to the mitzva of burial? The verse states: “But you shall bury him [kavor tikberennu],” doubling the verb for emphasis. From here there is a hint to the mitzva of burial in the Torah. The Gemara relates: King Shapur, the monarch of Persia, once said to Rav Ḥama: From where in the Torah is there a hint to the mitzva of burial? What proof is there that the dead must be buried and not treated in some other manner? Rav Ḥama was silent and said nothing to him, as he could not find a suitable source. Rav Aḥa bar Ya’akov said: The world has been handed over to the foolish, as Rav Ḥama should have said to King Shapur that the mitzva of burial is derived from the verse: “But you shall bury him” (Deuteronomy 21:23).

(1) That is that He commanded us to bury those killed by the court on the day that they are killed. And that is His, may He be exalted, saying, "but you must surely bury him on that day" (Deuteronomy 21:23). And the language of the Sifrei (Sifrei Devarim 221:7) is, "'But you must surely bury him' - that is a positive commandment." And the law is the same for the other dead - meaning to say, that we bury all the dead of Israel on the day of their death. And therefore a corpse that has no one to be involved with its burial is called a corpse of commandment (met mitzvah) - meaning a corpse about which it is a commandment upon everyone to bury it, by His saying, "but you must surely bury him." And the regulations of this commandment have already been explained in the sixth [chapter] of Sanhedrin. (See Parashat Ki Tetzei.)

(1) One who places his dead in a coffin and did not bury it in the earth, transgresses thereby a [negative command] because he keeps the dead over night [unburied]. If he placed him in a coffin and buried it in the earth, he does not transgress [a negative command] on his account. Nevertheless, it is [more] appropriate to bury him in the earth proper even [when he is buried] outside the Land [of Israel].

[Burial in the ground] is a accepted by us as a rabbinic mitzvah.

(1) A eulogy is an honor for the deceased. Therefore we compel the heirs to pay the wages of the men and women who recite laments and they eulogize him. If the deceased directed that he not be eulogized, we do not eulogize him. If, however, he directed that he not be buried, we do not heed him, for burial is a mitzvah, as Deuteronomy 21:22 states: "And you shall certainly bury him."

It is good to bury in the ground, for burial in real ground is a mitzvah, even outside of Israel. In every place there is a custom. Some bury in caves and some holes. Some in caskets and some without caskets. According to all opinions, the deceased is places on their back with their face up.

[On Shabbat,] if a fire occurs in a courtyard where there is a corpse, the reason it is forbidden to remove it is because there is no disgrace to the dead when the body is burned.