Faith cometh by hearing, and hearing by the word of God, Romans 10:17. It being the ordinary means which God hath appointed; the apostles themselves make use of it towards the conviction of this people. The number of the hearers is not intended to be set here, or in any other place; but either these five thousand were such as were converted at this sermon, or rather the number converted by St. Peter's former sermon, Acts 2:14-40, were at this sermon made thus many; howsoever, the increase which God gave was very great.
Related Commentaries of Acts 4:4
Acts 4:4
4 Howbeit many of them which heard the word believed; and the number of the men was about five thousand.