The first statement with "would" is correct. The use of "will" does not work here.
"Would come" is the conditional tense which indicates a future act from the perspective of the past. Since he said it an hour ago, he refers to an event that will occur in his future (even if it is in the past).
The second sentence might work like this: An hour ago he said: "I will come here tonight." It has to be a direct quote because it is the future (will) from a present perspective.