Perhaps God initiated this command in response to the incident of Sabbath-breaking just mentioned. The Israelites were to wear tassels on the four corners of their upper outer garments ( Deuteronomy 22:12). The text does not explain the size of the tassels, but old pictures of tassels on garments that ancient Near Easterners wore show that they were about six inches long. [source][source][source]
"The tassels were in fact extensions of the hem, as we learn from innumerable illustrations in ancient Near Eastern art. [source][source][source]
"To understand the significance of the tassel, we must first understand the significance of the hem.... The hem of the outer garment or robe made an important social statement. It was usually the most ornate part of the garment. And the more important the individual, the more elaborate and the more ornate was the embroidery on the hem of his or her outer robe.... [source][source][source]
"The significance of the hem and of its being cut off is reflected in a famous biblical episode [1].... [source][source][source]
"The requirement of a blue cord ... in the tassels lends further support to the notion that the tassels signified nobility because the blue dye used to color the threads was extraordinarily expensive.... [source][source][source]
"The Bible apparently assumed that even the poorest Israelite could afford at least four blue threads, one for each tassel.... Thus, weaving a blue thread ... into the tassel enhances its symbolism as a mark of nobility. [source][source][source]
"The tassel with a thread of blue signified more than royalty or nobility, however. It also signified the priesthood." [2][source]
The article just quoted also contains reproductions of ancient Near Eastern pictures of people wearing garments with tassels on them. The Israelite was to fasten the tassel to the garment with a blue thread, or it had to contain a blue thread. The blue color, as noted in our study of the tabernacle coverings, probably symbolized heavenly origin and royalty. Thus God apparently wanted the blue thread to remind the Israelites of their holy calling as a kingdom of priests. These tassels reminded the Israelites of their privileged position in the world and their noble and holy calling. [source][source][source]
The tassels were clearly a visual aid for the Israelites and probably produced a conditioned response in the minds of pious Jews (cf. Deuteronomy 6:6-9). They did not bring to mind any one commandment but reminded the observer that he should observe all of God"s laws. He was distinct by virtue of his calling, as was the garment he observed. Perhaps God also chose the outer garment because the Israelites were as His outer garment by which the world recognized Him. His people were to be an adornment to Him (cf. Titus 2:10). Thus God specified something that would warn His people before they sinned; He did not just specify punishment after they sinned. [source][source][source]
"There is an intentional selection behind the collections of laws found throughout the Pentateuch. The purpose of that selection appears clear enough. In reading through these laws we can readily see that God is concerned about every detail of human life. Nothing is too small or unimportant. It all has to be made available and dedicated to him." [3][source]
This legislation is the basis for the custom of wearing a tallis or prayer shawl that modern observant Jews still wear. It is also the basis for the flag of the modern state of Israel"s blue color. [source][source][source]