Adam Clarke on Acts 2:15

But the third hour of the day - That is, about nine o'clock in the morning, previously to which the Jews scarcely ever ate or drank, for that hour was the hour of prayer. This custom appears to have been so common that even the most intemperate among the Jews were not known to transgress it; Peter therefore spoke with confidence when he said, these are not drunken - seeing it is but the third hour of the day, previously to which even the intemperate did not use wine.