The readers should understand that David intended for laborers to do the actual work. Alternate translation: "it was my intention to oversee the building of the house myself" (See: [[rc://en/ta/man/translate/figs-metonymy]])
The reflexive "myself" means that David originally planned to build the temple. Alternate translation: "that I would be the one to build the temple" (See: [[rc://en/ta/man/translate/figs-rpronouns]])