When the day of Pentecost came, they were all together in one place.
The timing was no accident: Pentecost gathered prodigious crowds from every nation, spreading the gospel's fame far and wide. The feast had commemorated the law given at Sinai fourteen centuries before; now the Holy Ghost came in fire and tongues to proclaim the evangelical law, not to one nation alone but to every creature.
AI summary
Commenting on Acts 2:1-4
And when the day of Pentecost was fully come, they were all with one accord in one place. (1) The Apostles being gathered together on a most solemn feast day in one place, that it might evidently appear to all the world that they all had one office, one Spirit, and one faith, are by a double sign from heaven authorised, and anointed with all...
1. And when. To be fulfilled is taken in this place for to come. For Luke beareth record again of their perseverance, when he saith that they stood all in one place until the time which was set them. Hereunto serveth the adverb, with one accord Furthermore, we have before declared why the Lord did defer the sending of his Spirit a whole month and a half.