John Wesley on 1 Samuel 25:28

The trespass - That is, which I have taken upon myself, and which, if it be punished, the punishment will reach to me. Sure house - Will give the kingdom to thee, and to thy house for ever, as he hath promised thee. And therefore let God's kindness to thee, make thee gentle and merciful to others; do not sully thy approaching glory with the stain of innocent blood; but consider, that it is the glory of a king, to profit by offences: and that it will be thy loss to cut off such as will shortly be thy subjects. The battles - For the Lord, and for the people of the Lord against their enemies; especially, the Philistines. And as this is thy proper work, and therein thou mayest expect God's blessing; so it is not thy work to draw thy sword in thy own private quarrel against any of the people of the Lord; and God will not bless thee in it. Evil hath not, &c. - Though thou hast been charged with many crimes by Saul and others; yet thy innocency is evident to all men: do not therefore by this cruel act, justify thine enemies reproaches, or blemish thy great and just reputation.