A.T. Robertson Commentary Matthew 3:11

"I indeed baptize you in water unto repentance: but he that cometh after me is mightier than I, whose shoes I am not worthy to bear: he shall baptize you in the Holy Spirit and [in] fire:" — Matthew 3:11 (ASV)

Mightier than I (ισχυροτερος μου). Ablative after the comparative adjective. His baptism is water baptism, but the Coming One "will baptize in the Holy Spirit and fire." "Life in the coming age is in the sphere of the Spirit. Spirit and fire are coupled with one preposition as a double baptism" (McNeile). Broadus takes "fire" in the sense of separation like the use of the fan. As the humblest of servants John felt unworthy to take off the sandals of the Coming One. About βασταζω see on Mt 8:17.