Korach's Techelet Tallit

(13) if the priest sees that the eruption has covered the whole body—he shall pronounce as pure the affected person, who is pure from having turned all white.

The Sages taught in a baraita: With regard to ritual fringes on a linen cloak, Beit Shammai deem the cloak exempt from ritual fringes due to the fact that the sky-blue strings must be made from wool, and there is a Torah prohibition against wearing a mixture of wool and linen. And Beit Hillel deem a linen cloak obligated in the mitzva of ritual fringes. And the halakha is in accordance with the statement of Beit Hillel.

(Numb. 16:1:) “Now Korah […] took.” What is written above the matter (in Numb. 15:38)? “Speak unto the Children of Israel and tell them to make tassels (zizit) for themselves.’” Korah quickly said to Moses, “In the case of a prayer shawl (tallit) which is all blue, what is the rule about it being exempt from [having] the tassel?” Moses said to him, “[Such a prayer shawl] is required to have the tassels.” Korah said to him, “Would not a prayer shawl which is all blue exempt itself, when four [blue] threads exempt it? In the case of a house which is full of [scriptural] books, what is the rule about it being exempt it from [having] the mezuzah (which contains only two passages of scripture)?” [Moses] said to him, “[Such a house] is required to have the mezuzah.” [Korah] said to him, “Since the whole Torah has two hundred and seventy-five parashiot in it and they do not exempt the house [from having the mezuzah], would the two parashiot which are in the mezuzah exempt the house?” [He also] said to him, “These are things about which you have not been commanded. Rather you are inventing them [by taking them] out of your own heart.” Here is what is written (in Numb. 16:1), “Now Korah […] took.” (Numb. 16:1:) “Now Korah […] took.” Now “took (rt.: lqh)” can only be a word of discord, in that his heart carried him away (rt.: lqh). Thus is [the word] used (in Job 15:12), “How your heart has carried you away (rt.: lqh) […].” This explains what Moses said to them (in Numb. 16:9), “Is it too small a thing for you that the God of Israel has separated you [from the congregation to draw you near unto Himself, to perform the service of the Lord's tabernacle …?” Plus] that whole passage up to (vs. 29), “If these people die the common death of every person.” The sages have said, “Korah was a great sage and was one of the bearers of the ark, as stated (in Numb. 7:9), ‘But to the children of Kohath He gave no [wagons], because they had the service of the holy objects, which they carried on their shoulders.’” Now Korah was the son of Izhar, [who was] the son of Kohath. When Moses said (in Numb. 15:38), “And put on the tassel of each corner a thread of blue,” what did Korah do? He immediately ordered them to make two hundred and fifty blue shawls for those two hundred and fifty heads of sanhedraot who rose up against Moses to wrap themselves in, just as it is stated (in Numb. 16:2), “And they rose up against Moses, together with two hundred and fifty men from the children of Israel.” And who are they? (Numb. 16:2, cont.:) “Princes of the congregation, chosen in the assembly, men of repute.” Korah arose and made them a banquet at which they all wrapped themselves in blue prayer shawls. [When] Aaron's sons came to receive their dues, [namely the] breast and right thigh, they arose against them and said to them, “Who commanded you to receive such? Was it not Moses? [If so,] we shall not give you anything, as the Holy One, blessed be He, has not commanded it.” They came and informed Moses. He went to placate them. They immediately confronted him, as stated (ibid.), “And they rose up against Moses.” And who were they? Elizur ben Shedeur and his companions (the princes), the men (according to Numb. 1:17) “who were mentioned by name.” Although the text has not publicized their [names], it has given clues to their [identity], so that you [can] identify them from the [various] verses. A parable: To what is the matter comparable? To a scion of good parentage who stole articles from the bathhouse. The owner of what was stolen did not want to publish his [name. Rather,] he began to give clues about his [identity]. When they said to him, “Who stole your articles,” he said, “A scion of good parentage, a tall person with beautiful teeth and black hair.” After he had given his clues, they knew who he was. So also here where the text has concealed them and not specified their names, it comes and gives clues to their [identity]. You know who they are. It is stated elsewhere (in Numb. 1:16), “These were elected by the congregation, princes of their ancestral tribes, heads of thousands within Israel.” Then it is written (in vs. 17), “So Moses and Aaron took these men who were mentioned by name.” Now here it is written (in Numb. 16:2-3), “princes of the congregation, elected by the assembly, men of renown. They gathered together against Moses and Aaron.”

MISHNA: The absence of the sky-blue [tekhelet] strings does not prevent fulfillment of the mitzva of ritual fringes with the white strings, and the absence of white strings does not prevent fulfillment of the mitzva with the sky-blue strings. If one has only one, he wears it without the other. Absence of the phylacteries of the arm does not prevent fulfillment of the mitzva of the phylacteries of the head, and absence of the phylacteries of the head does not prevent fulfillment of the mitzva of the phylacteries of the arm. If one has only one, he dons it without the other.