Midrasch zu Jirmejahu 16:4

R. Jochanan, in the name of R. Simon b. Jochai, said: "Whence do we learn that if one leaves a dead body over night he violates a prohibitory law? It is said (Deut. 21, 23) Thou shalt not leave over night his corpse on the tree." R. Jochanan said again in the name of R. Simon b. Jochai: "Where is to be found in the Torah an intimation for burying a dead body. It is said. But thou shalt surely bury him." King Sabur questioned R. Chama: "Whence do you deduce from the Torah that one must be buried?" And the latter remained silent — without an answer. R. Acha b. Jacob said: "He is delivered into the hands of fools. Why did he not answer from the above-cited verse?" Because the above is to be explained to mean that a coffin and shroud are to be prepared for him, and the doubling of the word Kabor he thinks does not refer to anything. But let him say: Because all the righteous were buried. This is only a custom, and not a command of the Torah. And why not say: Because the Holy One, praised be He! buried Moses? It may be said that this also was not to change the custom. Come, listen! (I Kings 14, 13) And all Israel shall mourn for him, and bury him. This also, was not to change the custom. But is it not written (Jer. 16, 4) They shall not be lamented for; nor shall they be buried? Jeremiah cautioned them, that with them there will be a change of custom.