The Passover affords a more than usually solemn day for baptism; when, withal, the Lord's passion, in which we are baptized, was completed. Nor will it be incongruous to interpret figuratively the fact that, when the Lord was about to celebrate the last Passover, He said to the disciples who were sent to make preparation, "You will meet a man bearing water." He points out the place for celebrating the Passover by the sign of water. After that, Pentecost is a most joyous space for conferring baptisms; wherein, too, the resurrection of the Lord was repeatedly proved among the disciples [Acts 1:3], and the hope of the advent of the Lord indirectly pointed to, in that, at that time, when He had been received back into the heavens [Acts 1:9], the angels told the apostles that "He would so come, as He had withal ascended into the heavens;" [Acts 1:11] at Pentecost, of course. But, moreover, when Jeremiah says, "And I will gather them together from the extremities of the land in the feast-day," he signifies the day of the Passover and of Pentecost, which is properly a "feast-day." However, every day is the Lord's; every hour, every time, is apt for baptism: if there is a difference in the solemnity, distinction there is none in the grace.
This grace was not in part, but his power was in full perfection; for as he who plunges into the waters and is baptized is encompassed on all sides by the waters, so were they also baptized completely by the Holy Spirit. The water, however, flows round the outside only, but the Spirit baptizes also the soul within, and that completely. And why do you wonder at this? Take an example from matter, a simple and common example, but one that helps the ordinary person. If the fire passing in through the mass of the iron makes the whole of it fire, so that what was cold becomes burning and what was black is made bright, if fire which is a body thus penetrates and works without hindrance in iron which is also a body, why wonder that the Holy Spirit enters into the very inmost recesses of the soul?
The Gospels, then, are a narrative of what Christ did and said, while the Acts are of what the other Paraclete said and did. Not that the Spirit did not do many things in the Gospels also, just as Christ here in Acts still works in people as he did in the Gospels, but then it was through the temple, while now it is through the apostles. Then the Spirit entered the virgin mother and fashioned the temple, now he enters into the souls of the apostles; then in the likeness of a dove, now in the likeness of fire. Why? There he showed the gentleness of the Lord, but here his also taking vengeance. He reminds them opportunely also of the judgment. For when the need was to forgive sin, there was need of much gentleness; but when we have obtained the gift, it is henceforth a time for judgment and examination.
But you shall be baptized with the Holy Spirit not many days from now. The apostles had not yet been baptized, not with water, but with the Holy Spirit, whom we understand they had already been baptized, either with John's baptism (as some suppose), or (what is more credible) with Christ's baptism. For the ministry of baptizing had not been such that it had baptized servants through whom others would be baptized, for the ministry of that memorable humility was not lacking, when He washed their feet. Therefore, when the Lord said: For John indeed baptized with water, He did not add: But you shall baptize, but: But you shall be baptized with the Holy Spirit. For neither the apostles nor their followers, who baptize even to this day in the Church, can baptize otherwise than John, that is, with water, but only by invoking the name of Christ, the interior power of the Holy Spirit is present, which, with a man providing the water, purifies both the souls and bodies of the baptized, which was not done in John's baptism. For the Spirit had not yet been given, because Jesus had not yet been glorified (John VII).
For John indeed baptized with water, but you will be baptized with the Holy Spirit. Baptisma in Greek is called tinctio in Latin. Wherefore, in some manuscripts we find it interpreted thus: For John indeed dipped with water, but you will be dipped in the Holy Spirit. Here the marvelous harmony of the words of the Lord and his precursor is evident. For he said to those whom he baptized, about the Lord: I baptized you with water, but he will baptize you with the Holy Spirit (Mark 1:8). And the Lord himself: John indeed baptized with water, but you will be baptized with the Holy Spirit. It should be noted as well that the baptism of the Lord in the Holy Spirit, which John had foretold, does not refer only to that time when the Apostles and other faithful of that time were baptized with water for the remission of sins, through the grace of the Holy Spirit given to them by the Lord; but also to this, when, with the Lord sending them, they received more fully the gifts of the same Spirit from heaven. But also now, whoever receives baptism for the remission of sins, is certainly baptized in the Holy Spirit, through whose gift they are both cleansed from all sins, and are aided so that they can progress in good deeds.
[AD 220] Tertullian on Acts 1:3-11