Acts 1:15

“And in those days Peter stood up, etc.] That is, in one of the days after Christ’s ascension, and before the day of Pentecost, whilst the disciples were waiting for the promise of the Spirit. The Ethiopic version reads, “on that day”; as if it was the same day they came first into Jerusalem, and went into the upper room; and which is likely enough; for no time was to be lost in choosing one in the room of Judas; when Peter, not only as a forward person, and who had been used to be the first mover and actor in any affair; but as willing to show his zeal for Christ, whom he had so lately denied, and as being the senior man in company, as well as the minister of the circumcision, rises, and…”

“in those days--of expectant prayer, and probably towards the close of them, when the nature of their future work began more clearly to dawn upon them, and the Holy Ghost, already "breathed" on the Eleven (Joh 20:22), was stirring in Peter, who was to be the leading spirit of the infant community (Mat 16:19). the number . . . about an hundred and twenty--Many, therefore, of the "five hundred brethren" who saw their risen Lord "at once" (Co1 15:6), must have remained in Galilee.”

“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 a thing, Luke 15:18. The reason why Peter did this may be seen in the notes 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 the notes on Matthew…”

“The number of persons together - Who were together in the upper room. were a hundred and twenty - But he had undoubtedly many more in other places; of whom more than five hundred saw him at once after his resurrection, Co1 15:6. Acts 1:16”

“Peter: Psa 32:5, Psa 32:6, Psa 51:9-13; Luk 22:32; Joh 21:15-17, the names, Rev 3:4, Rev 11:13 \*Gr. an: Act 21:20 \*Gr: Mat 13:31; Joh 14:12; Co1 15:6 Acts 1:16”