Habakkuk was told to write the vision and make it plain. This was done in order for the one that reads to have an understanding in order to run. This vision was for an appointed time. What is it (the vision)? We need to know!
Hab 2:2 And the LORD answered me, and said, Write the vision, and make it plain upon tables, that he may run that readeth it. 3 For the vision is yet for an appointed time, but at the end it shall speak, and not lie: though it tarry, wait for it; because it will surely come, it will not tarry. 4 Behold, his soul which is lifted up is not upright in him: but the just shall live by his faith.
We find that faith is important for the vision to be made plain to those that are upright, as is said, “the JUST shall live by faith!” The justified ones!