Matthew Poole and continuators on 1 Chronicles 15:23

23 And Berechiah, and Elkanah were door-keepers for the ark .

They were appointed to keep the Door of the Tent in which the Ark was to be put and kept that no unallowed person might press in and touch it; and in like manner they were to attend upon the Ark in the Way, and to guard it from the press and touch of profane Hands; for which End these two went before the Ark, as their other two Brethren mentioned in the close of v. 24. came after it, that so it might be guarded on all sides: which, how necessary it was to be done, sufficiently appears from the danger of coming too near the Ark or to look into it, which was exemplified in the Bethshemites, 1 Sam. 6. 19.