Do thyself no harm - This is the solemn command of religion in his case, and in all others. It enjoins upon people to do themselves no harm by self-murder, whether by the sword, the pistol, the halter; by intemperance, by lust, or by dissipation. In all cases, Christianity seeks the true welfare of man. In all cases, if it were obeyed, people would do themselves no harm. They would promote their own best interests here, and their eternal welfare hereafter.

Do thyself no harm - As it was now dark, being midnight, St. Paul must have had a Divine intimation of what the jailor was going to do; and, to prevent it, cried out aloud, Do thyself no harm, for we are all here.

(17) But Paul cried with a loud voice, saying, Do thyself no harm: for we are all here.
(17) In means which are especially extraordinary, we should not move our foot forward, unless God goes before us.

But Paul cried with a loud voice,.... Knowing by divine revelation, what the jailer was about to do; though being in the innermost prison, in a dark dungeon, he could not see him, unless it can be thought, that the opening of the doors had let in light sufficient; and it may be also, that he knew in the same way, what designs of grace God had towards this man and his family:
saying, do thyself no harm; which is an instance of great tenderness, humanity, and love, to one that had used him and his companion with so much severity and cruelty:
for we are all here; not only Paul and Silas, but the rest of the prisoners also; who either being so intent upon hearing the prayers and praises of the apostles, or so terrified with the earthquake, that they took no notice of their bands being loosed, and so never thought or attempted to make their escape; and as for Paul and Silas, all this happened to them, not for their deliverance in this way, as in the case of Peter, but to show the power of God, what he could do, and his presence with his servants.

But Paul cried with a loud voice--the better to arrest the deed.
Do thyself no harm, for we are all here--What divine calmness and self-possession! No elation at their miraculous liberation, or haste to take advantage of it; but one thought filled the apostle's mind at that moment--anxiety to save a fellow creature from sending himself into eternity, ignorant of the only way of life; and his presence of mind appears in the assurance which he so promptly gives to the desperate man, that his prisoners had none of them fled as he feared. But how, it has been asked by skeptical critics, could Paul in his inner prison know what the jailer was about to do? In many conceivable ways, without supposing any supernatural communication. Thus, if the jailer slept at the door of "the inner prison," which suddenly flew open when the earthquake shook the foundations of the building; if, too, as may easily be conceived, he uttered some cry of despair on seeing the doors open; and, if the clash of the steel, as the affrighted man drew it hastily from the scabbard, was audible but a few yards off, in the dead midnight stillness, increased by the awe inspired in the prisoners by the miracle--what difficulty is there in supposing that Paul, perceiving in a moment how matters stood, after crying out, stepped hastily to him, uttering the noble entreaty here recorded? Not less flat is the question, why the other liberated prisoners did not make their escape:--as if there were the smallest difficulty in understanding how, under the resistless conviction that there must be something supernatural in their instantaneous liberation without human hand, such wonder and awe should possess them as to take away for the time not only all desire of escape, but even all thought on the subject.

But Paul cried - As they were all then in the dark, it is not easy to say, how Paul knew of the jailer's purpose; unless it were by some immediate notice from God, which is by no means incredible. With a loud voice - Through earnestness, and because he was at some distance. Do thyself no harm - Although the Christian faith opens the prospect into another life, yet it absolutely forbids and effectually prevents a man's discharging himself from this.