2 Corinthians 13:3

Since ye seek a proof of Christ speaking in me
This is the reason why he was determined, that should he come among them, he would not spare them, because they called in question his apostleship, and demanded a proof of it; which, of all men, they had the least reason to do; for they themselves were the seals of his apostleship, and the signs of an apostle had been done among them; they queried whether he was an ambassador of Christ, and was sent by him, and in his name; whether the message he came with was from him, and whether the Gospel he preached was his voice; and particularly whether he had such a power to punish delinquents, as he threatened them with the exercise of; a strange infatuation of the false apostles this, since Christ, who sent him, was with him, and spoke in him, and by him:

which to you-ward,
says he,

is not weak, but is mighty in you;
the Gospel of Christ, at the first preaching of it to them by him, was the power of God unto salvation to them; and was attended with divers signs and wonders, and gifts of the Holy Ghost; and besides, they had instances of the power of Christ towards them in an awful way, in punishing sinners; as in the delivery of the incestuous person to Satan, which was done by his Spirit being with them when assembled; and by smiting many of them with sickness, diseases, and infirmities, and with death itself, who had sinned, ( 1 Corinthians 5:4 1 Corinthians 5:5 ) ( 11:30 ) . Wherefore, seeing after all these instances of the voice and power of Christ in him, they yet questioned his apostolical authority, and sought proof of it; and especially since this was not so much a tempting of him, as a tempting of Christ in him, he was resolved not to spare them.