Speak to the children of Yisra᾽el, and bid them that they make them fringes in the corners of their garments throughout their generations, and that they put upon the fringe of each corner a thread of blue:
And Mordecai went forth from the presence of the king in royal apparel of blue and white, and with a great crown of gold, and with a rob of fine linen and purple; and the city of Shushan shouted and was glad.
From what time is the שמע to be said in the morning? From the time man can distinguish between blue and white. R. Eleazar saith, "between blue and leek-green." And it may be said, "until the sun shines forth [over the mountain tops]." R. Joshua saith, "until the third hour," for such is the habit of royal princes who rise at the third hour. He who says the שמע after that time loses nothing, [but is] like any man who reads in the Torah.
As for the Tabernacle, make it of ten strips of cloth; make these of fine twisted linen, of blue, purple, and crimson yarns, with a design of cherubim worked into them.
The tattooing that is spoken of in the Torah is cutting the flesh and filling the place with blue or ink or other dyes that are inscribed. And this was the custom of the idolaters who inscribed themselves for the sake of their idolatry as if to say he is a servant sold to it and inscribed for its service. And when one inscribes with one of these inscribing items after cutting in any place on the body, whether a man or a woman, he or she is to be lashed. One who wrote but did not inscribe with color or who inscribed with color, but did not write with cutting is not liable. Only when he writes and dyes as it is written, "an inked writing (Leviticus 19:28)." To whom does this apply? To the one who does the tattooing, but the one who is tattooed is not liable unless he assisted in creating this deed, but if he did nothing he is not lashed.
And thou shalt make a breastplate of judgment, the work of the skillful workman; like the work of the ephod thou shalt make it: of gold, of blue, and purple, and scarlet, and fine twined linen, shalt thou make it.
And all the women that were wise-hearted did spin with their hands, and brought that which they had spun, the blue, and the purple, the scarlet, and the fine linen.
Incidental to the halakhic statement in his name, the Gemara also cites another statement that Rava bar Meḥasseya said that Rav Ḥama bar Gurya said that Rav said: One who gives a gift to another must inform him that he is giving it to him. As it is stated: “Only keep My Shabbatot for it is a sign between Me and you for your generations to know that I am God Who sanctifies you” (Exodus 31:13). When the Holy One, Blessed be He, gave Shabbat to Israel, He told Moses to inform them about it. That was also taught in a baraita: The verse states: “For I am God Who sanctifies you,” meaning that the Holy One, Blessed be He, said to Moses: I have a good gift in My treasure house and Shabbat is its name, and I seek to give it to Israel. Go inform them about it. From here Rabban Shimon ben Gamliel said: One who gives a gift of bread to a child needs to inform his mother that he gave it to him. The Gemara asks: What does he do to the child, so that his mother will know that he gave him a gift? Abaye said: He should smear him with oil or place blue shadow around his eye in an obvious manner. When the mother of the child notices and asks him about it, he will tell her that so-and-so gave him a piece of bread. The Gemara asks: And now that we are concerned about witchcraft involving oil or eye shadow, what should one who gives a gift do? Rav Pappa said: He should smear him with food of the same type that he gave him to eat.
The robe for the ephod was made of woven work, of pure blue.
Blue thread, wherever it is mentioned in the Torah, is wool dyed azure, the color of the firmament seen in a blue sky when the sun is shining. The blue thread mentioned in connection with fringes must be dyed with a special dye which retains its lustre without change. Wool that has not been dyed in this dye is unfit for use as the blue thread, even though it is of the color of the sky; as, for instance, if it has been dyed with indigo, lamp-black or other darkening material, it cannot be used as the thread of blue with the fringe. The wool of a ewe whose dam was a she-goat is unfit for use as fringes.
And he made the veil of blue, and purple, and crimson, and fine linen, and worked keruvim on it.
פתיל תכלת, our sages explained the reason for the blue colour as designed to remind the viewer of the blueness of the ocean, which in turn resembles the blueness of the sky reminding man of the throne of G’d’s glory situated in the celestial spheres.(compare Sifri on our verse).
The Gemara answers: As it is taught in a baraita that Rabbi Meir would say: What is different about sky-blue from all other colors such that it was specified for the mitzva of ritual fringes? It is because sky-blue dye is similar in its color to the sea, and the sea is similar to the sky, and the sky is similar to the Throne of Glory, as it is stated: “And they saw the God of Israel; and there was under His feet the like of a paved work of sapphire stone, and the like of the very heaven for clearness” (Exodus 24:10). This verse shows that the heavens are similar to sapphire, and it is written: “And above the firmament that was over their heads was the likeness of a throne, as the appearance of a sapphire stone” (Ezekiel 1:26). Therefore, the throne is similar to the heavens. The color of sky blue dye acts as an indication of the bond between the Jewish people and the Divine Presence.
They shall take a blue woolen cloth and they shall cover the Menorah that illuminates and its lamps, its tongs and its scoops and all of its oil vessels; those with which you use to perform its service.