The speaker is careful not to name the one plotting the evil. This can be translated in active form. Alternate translation: "someone is plotting to do evil things to our master" (See: [[rc://en/ta/man/translate/figs-activepassive]])
The speaker speaks of David as if David were another person to show that he respects David. Alternate translation: "you" (See: [[rc://en/ta/man/translate/figs-pronouns]])