Albert Barnes on John 5:3

Impotent folk. Sick people; or people who were weak and feeble by long disease. The word means those who were feeble rather than those who were afflicted with acute disease.

Halt. Lame.

Withered. Those who were afflicted with one form of the palsy that withered or dried up the part affected. Mt 4:24.

Moving of the water. It appears that this pool had medicinal properties only when it was agitated or stirred. It is probable that at regular times or intervals the fountain put forth an unusual quantity of water, or water of peculiar properties, and that about these times the people assembled in multitudes who were to be healed.