Albert Barnes Commentary 1 Kings 1:9

"And Adonijah slew sheep and oxen and fatlings by the stone of Zoheleth, which is beside En-rogel; and he called all his brethren, the king`s sons, and all the men of Judah, the king`s servants:" — 1 Kings 1:9 (ASV)

Adonijah’s feast was probably of a sacrificial character, intended to inaugurate him as king. Compare the “sacrifices” of Absalom (2 Samuel 15:12).

Zoheleth - No satisfactory explanation has been given for this name. Large blocks of stone always attract attention in the East and receive names which are often drawn from some trivial circumstance. Sinai and Palestine are full of such “Hajars,” which correspond to the “Ebens” or “stones” of Holy Scripture. (Joshua 4:9; 1 Samuel 6:14).