Numbers 15:37-39

Later, the LORD said to Moses, “Speak to the Israelites and tell them that throughout the generations to come they are to make for themselves tassels for the corners of their garments, with a blue cord on each tassel. These will serve as tassels for you to look at, so that you may remember all the commandments of the LORD, that you may obey them and not prostitute yourselves by following your own heart and your own eyes.