Numbers 15:38-39
15:38 “Speak to the Israelites and tell them to make tassels for themselves on the corners of their garments throughout their generations, and put a blue thread on the tassel of the corners.
15:39 You must have this tassel so that you may look at it and remember all the commandments of the Lord and obey them and so that you do not follow after your own heart and your own eyes that lead you to unfaithfulness.