Albert Barnes Commentary 1 Kings 3:11

"And God said unto him, Because thou hast asked this thing, and hast not asked for thyself long life, neither hast asked riches for thyself, nor hast asked the life of thine enemies, but hast asked for thyself understanding to discern justice;" — 1 Kings 3:11 (ASV)

Your enemies - for example, Hadad the Edomite (1 Kings 11:14–22) and Rezon the son of Eliadah (1 Kings 11:23–25), whom Solomon might well have wished to remove.