Hachilah

the darksome hill, one of the peaks of the long ridge of el-Kolah, running out of the Ziph plateau, "on the south of Jeshimon" (i.e., of the "waste"), the district to which one looks down from the plateau of Ziph (1Sam 23:19). After his reconciliation with Saul at Engedi (1Sam 24:1-8), David returned to Hachilah, where he had fixed his quarters. The Ziphites treacherously informed Saul of this, and he immediately (1Sam 26:1-4) renewed his pursuit of David, and "pitched in the hill of Hachilah." David and his nephew Abishai stole at night into the midst of Saul's camp, when they were all asleep, and noiselessly removed the royal spear and the cruse from the side of the king, and then, crossing the intervening valley to the height on the other side, David cried to the people, and thus awoke the sleepers. He then addressed Saul, who recognized his voice, and expostulated with him. Saul professed to be penitent; but David could not put confidence in him, and he now sought refuge at Ziklag. David and Saul never afterwards met. (1Sam 26:13-25).

EBD - Easton's Bible Dictionary