Bede the Venerable
Catena Aurea · Lukasevangelium 3
And as the people were in expectation, and all men mused in their hearts of John, whether he were the Christ, or not; John answered, saying unto them all, I indeed baptize you with water; but one mightier than I cometh, the latchet of whose shoes I am not worthy to unloose: he shall baptize you with the Holy Ghost and with fire. Whose fan is in his hand, and he will throughly purge his floor, and will gather the wheat into his garner; but the chaff he will burn with fire unquenchable.
The Holy Spirit also may be understood by the word fire, for He kindles with love and enlightens with wisdom the hearts which He fills. Hence also the Apostles received the baptism of the Spirit in the appearance of fire. There are some who explain it, that now we are baptized with the Spirit, hereafter we shall be with fire, that as in truth we are now born again to the remission of our sins by water and the Spirit, so then we shall be cleansed from certain lighter sins by the baptism of purifying fire.