1 Thessalonians 5:3

"When they are saying peace and safety, then sudden destruction cometh upon them, as travail upon a woman with child; and they shall in nowise escape." Here he has glanced at something which he has also said in his second Epistle. For since they indeed were in affliction, but they that warred on them at ease and in luxury, and then while he comforted them in their present sufferings by this mention of the Resurrection, the others insulted them with arguments taken from their forefathers, and said, When will it happen? But it may be worth while to ask, If Antichrist comes, and Elias comes, how is it "when they say Peace and safety," that then a sudden destruction comes upon them? For these things do not permit the day to come upon them unawares, being signs of its coming. But he does not mean this to be the time of Antichrist, and the whole day, because that will be a sign of the coming of Christ, but Himself will not have a sign, but will come suddenly and unexpectedly. For travail, indeed, you say, does not come upon the pregnant woman unexpectedly: for she knows that after nine months the birth will take place. And yet it is very uncertain. For some bring forth at the seventh month, and others at the ninth. And at any rate the day and the hour is uncertain. With respect to this therefore, Paul speaks thus. And the image is exact. For there are not many sure signs of travail; many indeed have brought forth in the high roads, or when out of their houses and abroad, not foreseeing it. And he has not only glanced here at the uncertainty, but also at the bitterness of the pain.