1 Samuel 26:9–11
9 And David said to Abishai, Destroy him not: for who can stretch forth his hand against lthe Lord’s anointed, and be guiltless? 10 David said furthermore, mAs the Lord liveth, nthe Lord shall smite him; or ohis day shall come to die; or he shall descend pinto battle, and perish. 11 The qLord forbid that I should stretch forth mine hand against lthe Lord’s anointed: but, I pray thee, take thou now the spear that is at his bolster, and the cruse of water, and let us go.
See Ruth 3:13.