Asa would have had his workers gather the gold and silver for him. Alternate translation: "Then Asa told his workers to take the silver ... of the king's house, and to take it" (See: [[rc://en/ta/man/translate/figs-metonymy]])
This means he spoke by means of his servants. Asa told his servants what to say to Ben Hadad and they did. The meaning of this can be made clear. Alternate translation: "Asa told his servants to say to Ben Hadad" or "Through his servants, Asa said to Ben Hadad" (See: [[rc://en/ta/man/translate/figs-metonymy]] and [[rc://en/ta/man/translate/figs-explicit]])