Albert Barnes Commentary Acts 1:15

"And in these days Peter stood up in the midst of the brethren, and said (and there was a multitude of persons [gathered] together, about a hundred and twenty)," — Acts 1:15 (ASV)

In those days. On one of the days intervening between the ascension of Jesus and the day of Pentecost.

Peter stood up. Peter standing up, or rising. This is a customary expression in the Scriptures when one begins to do something (Luke 15:18). The reason why Peter did this may be seen in Barnes' note on Matthew 16:16-17.

It is not improbable, besides, that Peter was the most aged of the apostles; and from his uniform conduct, we know that he was the most ardent. It was perfectly characteristic, therefore, for him to introduce the business of the election of a new apostle.

The disciples. This was the name which was given to them as being learners in the school of Christ (see Barnes on Matthew 5:1).

The number of the names. The number of the persons, or individuals. The word name is often used to denote the person (Revelation 3:4; Acts 4:12; Acts 18:15; Ephesians 1:21).

In Syriac, it is, "the assembly of men was about one hundred and twenty." This was the first assembly convened to transact the business of the church, and it is not a little remarkable that the vote in so important a matter as electing an apostle was by the entire church.

This settles the question that the election of a minister and pastor should be by the church, and not be imposed on them by any right of presentation by individuals or by any ecclesiastical body.

If a case could ever occur where a minister should be chosen by the ministry only, such a case was here in the election of another apostle.

And yet, in this, the entire church had a voice. Whether this was all the true church at this time does not appear from the history.

This expression cannot mean that there were no more Christians, but that these were all that had convened in the upper room. It is almost certain that our Saviour had, by His own ministry, brought many others to be His true followers.