Albert Barnes Commentary John 8:9

"And they, when they heard it, went out one by one, beginning from the eldest, [even] unto the last: and Jesus was left alone, and the woman, where she was, in the midst." — John 8:9 (ASV)

Beginning at the eldest. Being conscious of more sins, they therefore desired to leave the Lord Jesus. The word eldest here probably refers not to age, but to honour—from those who were in highest reputation to the lowest in rank. This consciousness of crime showed that the state of public morals was exceedingly corrupt and justified the declaration of Jesus that it was an adulterous and wicked generation (Matthew 16:4).

Alone. Jesus alone was left with the woman.

In the midst. Her accusers had gone out, leaving Jesus and the woman. However, it is by no means probable that the people had also left them. As this was in the temple on a public occasion, they were doubtless still surrounded by many. This is evident from the fact that Jesus immediately (John 8:12) addressed a discourse to the people present.