Adam Clarke on Acts 4:4

The number - was about five thousand - That is, as I understand the passage, the one hundred and twenty which were converted before pentecost, the three thousand converted at pentecost, and one thousand eight hundred and eighty converted since the conversion of the three thousand; making in the whole five thousand, or ὡσει about that number: there might have been more or less; the historian does not fix the number absolutely. A goodly flock in one city, as the commencement of the Christian Church! Some think all the five thousand were converted on this day; but this is by no means likely.