Jamieson, Fausset and Brown on 1 Samuel 22:17-18

17-18. the footmen that stood about him--his bodyguard, or his runners (1Sa 8:11; 2Sa 15:1; 1Ki 1:5; 1Ki 14:28), who held an important place at court (2Ch 12:10). But they chose rather to disobey the king than to offend God by imbruing their hands in the blood of his ministering servants. A foreigner alone (Psa 52:1-3) could be found willing to be the executioner of this bloody and sacrilegious sentence. Thus was the doom of the house of Eli fulfilled [1Sa 2:30-36].