Harming someone is spoken of as if it were placing one's hand on that person. Here, Saul is referring to killing David. AT: "I will not be the one to kill him; I will let the Philistines kill him" (See: [[rc://en/ta/man/translate/figs-metaphor]] and [[rc://en/ta/man/translate/figs-euphemism]])
David uses this rhetorical question to emphasize that he is not worthy of being Saul's son-in-law. AT: "I am nobody and neither my relatives nor my father's family are important enough in Israel ... to the king." (See: [[rc://en/ta/man/translate/figs-rquestion]])