He lay down upon him. We know that the apostles, in working miracles, did sometimes use certain external rites, whereby they might give the glory to God, the author. And now, whereas Paul doth stretch himself upon the young man, I think it was done to no other end, save only that he might more easily stir up himself unto prayer. It is all one as if he should mix himself with the dead man, [1] And, peradventure, this was done for the imitation of Elisha, of whom the sacred history doth report the same thing (2 Kings 4:34). Yet the vehemency of his affection did more move him than the emulation of the prophet. For that stretching of himself upon him doth more provoke him to crave his life with all his heart at the hands of the Lord. So when he embraceth the body of the dead man, by this gesture he declared that he offered it to God to be quickened, and out of the text we may gather that he did not depart from embracing it until he knew that the life was restored again. Be ye not troubled. We must note that Paul took great care principally for this cause, lest that sorrowful event should shake the faith of the godly, and should trouble their minds. Nevertheless, the Lord did, as it were, seal up and establish [2] that last sermon which Paul made at Troas. When he saith that his soul is in him, he doth not deny that he was dead, because by this means he should extinguish the glory of the miracle; but the meaning of these words is, that his life was restored through the grace of God. I do not restrain that which followeth, to wit, that they were greatly comforted through the joy which they had by reason of the young man which was restored to life; but I do also comprehend the confirmation of faith, seeing God gave them such an excellent testimony of his love.

Footnotes

1 - "Perinde agit, acsi se misceret cum mortuo," he acts just as if he were mixing himself up with the young man.

2 - "Quasi insculpto sigillo apud eos sancivit," did sanction to them as with the impress of the seal.

And fell on him - Probably stretching himself on him as Elisha did on the Shunammite's son, 2-Kings 4:33-35. It was an act of tenderness and compassion, evincing a strong desire to restore him to life.
Trouble not yourselves - They would doubtless be thrown into great consternation by such an event. Paul therefore endeavoured to compose their minds by the assurance that he would live.
For his life is in him - He is restored to life. This has all the appearance of having been a miracle. Life was restored to him as Paul spoke.

And Paul - fell on him - Επεπεσεν αυτῳ, Stretched himself upon him, in the same manner as Elisha did on the Shunammite's son, 2-Kings 4:33-35; though the action of lying on him, in order to communicate warmth to the flesh, might not have been continued so long as in the above instance; nor indeed was it necessary, as the natural warmth had not yet left the body of Eutychus; but the son of the Shunammite had been some time dead.

And Paul went down,.... From the upper room, where they were assembled, into the court, yard, or street, where he fell; or into the lower room of the house, where he was brought when taken up. The apostle might see him fall, or he might be told of it, or he might have an intimation of it from the Spirit of God, by whom he might be impressed to go down, in order to work a miracle, for the confirmation of the Gospel he was preaching:
and fell on him, and embracing him; praying over him, as Elijah and Elisha did, 1-Kings 17:21 and the like effect followed:
said, trouble not yourselves; which speech perhaps was addressed to the friends and relations of the young man; or to the disciples present, who were concerned at this accident, both for the young man's sake, and lest it should be improved to the disadvantage of the Gospel by the enemies of it,
For his life, or "soul"
is in him; it being returned upon the apostle's falling on him, and praying over him; or he said this as being fully assured that it would return, in like manner as Christ said concerning Jairus's daughter, Luke 8:52.

Paul . . . fell on him--like Elisha (2-Kings 4:34).
his life is in him--now restored; compare Mark 5:39.

Paul fell or him - It is observable, our Lord never used this gesture. But Elijah and Elisha did as well as Paul. His life is in him - He is alive again.