Adam Clarke on Acts 8:23

The gall of bitterness - A Hebraism for excessive bitterness: gall, wormwood, and such like, were used to express the dreadful effects of sin in the soul; the bitter repentance, bitter regret, bitter sufferings, bitter death, etc., etc., which it produces. In Deu 29:18, idolatry and its consequences are expressed, by having among them a root that beareth Gall and Wormwood. And in Heb 12:15, some grievous sin is intended, when the apostle warns them, lest any root of Bitterness springing up, trouble you, and thereby many be defiled.

Bond of iniquity - An allusion to the mode in which the Romans secured their prisoners, chaining the right hand of the prisoner to the left hand of the soldier who guarded him; as if the apostle had said, Thou art tied and bound by the chain of thy sin; justice hath laid hold upon thee, and thou hast only a short respite before thy execution, to see if thou wilt repent.