This is Elijah (auto estin Eleia). Jesus here endorses John as the promise of Malachi. The people understood Malachi 4:1 to mean the return of Elijah in person. This John denied as to himself ( John 1:21 ). But Jesus affirms that John is the Elijah of promise who has come already ( Matthew 17:12 ). He emphasizes the point: "He that hath ears to hear, let him hear."