In Numbers 15:38-40, God instructs the Israelites to make tassels on the corners of their garments. These tassels are to be made with blue thread, serving as a reminder of God's commandments and the importance of following them. The passage emphasizes the significance of remembering and obeying God's laws. By looking at the tassels, the Israelites are encouraged to live righteously and avoid sinful behavior, reinforcing their identity as God's chosen people and their commitment to His teachings.