I Chronicles - Chapter 28
It's Divinely Inspired, Okay?
David called a gathering of the leaders of the people and his officials. Though he was old and infirm, he rose to address them.
"Listen, my brothers," he said. "I intended to build a Temple to G-d but I was denied the privilege. But G-d selected me as king and He has granted me an eternal dynasty with Solomon succeeding me. It is Solomon who will build G-d's Temple. Now I charge all of you with pursuing G-d's commandments and doing His will so that your descendants will be able to reside in our land forever. And you, Solomon, serve G-d wholeheartedly. If you seek Him, He will be there for you. If you abandon Him, you'll never see Him again. Fulfill His word to build the Temple."
David then gave Solomon the blueprints for various parts the Temple. These plans were Divinely revealed and were immutable. David also gave Solomon the various work rotations he had drawn up, which were apparently also Divinely inspired. David turned over to Solomon control of all the resources he had stockpiled, as well as instructions as to what was to be made with them. All the instructions that G-d had given were written down and David handed them over to Solomon. (It's not entirely clear to whom G-d gave the plans for the Temple - Moses? Samuel? Nathan? David himself? But whenever - and to whomever - G-d revealed them, this chapter makes abundantly clear that the design of the Temple is of Divine origin.)
Solomon was encouraged by his father to strengthen himself and to persevere in building G-d's Temple. If he did this, David said, G-d would be with him throughout the project.