1 And it happened, while Apollos was at Corinth, that Paul, having passed through the upper regions, came to Ephesus. And finding some disciples
2 He said to them, “Did you receive the Holy Spirit when you believed?”
So they said to him, “We have not so much as heard whether there is a Holy Spirit.”
3 And he said to them, “Into what then were you baptized?” So they said, “Into John’s baptism.”
4 Then Paul said, “John indeed baptized with a baptism of repentance, saying to the people that they should believe on Him who would come after him, that is, on Christ Jesus.”
5 When they heard this, they were baptized in the name of the Lord Jesus.
6 And when Paul had laid hands on them, the Holy Spirit came upon them, and they spoke with tongues and prophesied.
7 Now the men were about twelve in all.
upper borders (v.1) — There were two routes from Pisidian Antioch to Ephesus. The more usual one, after leading sixty miles southwest, joined the great throroughfare from the east at Apamea, and so passed down the valley of the Lycus by way of Colossae and Laodicea. The other road was more direct and, avoiding Apamea, passed over higher ground, following the river Cayster, to Ephesus — the whole distance being about 200 miles. In warm weather, the higher altitude would be preferable, though it was more toilsome for ordinary traffic. It is, clearly, to this road along the “upper border” that reference is here made. — The Acts of the Apostles, by Thomas Walker, pages 406-407.
Some commentaries believe these men learned from Apollos before he heard about grace from Aquila and Priscilla (18:25). But this is unlikely because he probably would have returned to them and taught them further truth.
since (v.2) = when
whether there is any Holy Spirit (v.2) — as disciples of John, and as Jews, these men almost certainly knew of the Holy Spirit (Matthew 3:11). The sense here is probably that they didn’t know if He had come.
It is Stam’s take that verse 5 is not saying that these 12 men were baptized by Paul after they heard what he said in verse 4. Instead, verse 5 records what the people mentioned in verse 4 did after they heard John’s message.
I’m not sure I fully understand this passage, and there isn’t any concensus among the commentaries. My guess is that these 12 men were Jews who had believed John the Baptist’s message but had somehow missed out on Pentecost. They met Paul before the kingdom offer had been fully withdrawn from Israel (in Acts 28), and so he brought them up to date on the current situation for Israel — this was their Pentecost-like kingdom offer, complete with the outworking of the Holy Spirit.