My bad, it's in his other Writings:
John Wesley's eighteenth-century conception of the Holiness movement developed the Pentecostal movement and the various Assemblies of God that emerged from roots in Methodism.
John Wesley on Slain in the Spirit:
April 4, 1764. — In the evening the Mayor and all the Gentry of the town were present; and so was our Lord in an uncommon manner. Some dropped down as dead; but, after a while, rejoiced with joy unspeakable. (WJW3:13)
July 14, 1759. —The Lord was wonderfully present, more than twenty persons feeling the arrows of conviction. Several fell to the ground; some of whom seemed dead; others, in the agonies of death, the violence of their bodily convulsions exceeding all description. There was also great crying and agonizing in prayer, mixed with deep and deadly groans on every side. (WJW2:11)
May 20, 1759. —Others fell down as dead; some sinking in silence; some with extreme pain and violent agitation. I stood on the pew-seat, as did a young man in the opposite pew, an able-bodied, healthy countryman; but in a moment, while he seemed to think of nothing less, down he dropped with a violence inconceivable; (WJW13, History Of The Methodists, Sec 74) 55
^
John Wesley claims HE was Slain in the Spirit! = [I stood on the pew-seat, as did a young man in the opposite pew, an able-bodied, healthy countryman; but in a moment, while he seemed to think of nothing less, down he dropped with a violence inconceivable;]
May 1, 1739. — The power of God (so I call it) came so mightily among us, that one, and another, and another, fell down as thunderstruck.
(WJW12, Letter To His Brother Samuel, dated May 10, 1739)56
June 12, 1742. — I preached on the righteousness of the Law and the righteousness of faith. While I was speaking, several dropped down as dead; (WJW1:5)
THERE IS LITERALLY 20 MORE EXAMPLES OF JOHN WESLEY WRITING DOWN HIS WITNESSING AND BEING SLAIN IN THE SPIRIT!
HE SPEAKS ALSO OF EXAMPLES OF HOLY LAUGHTER!
If you wish I can post several of those?
Overcome By Convulsions
At Wapping June 15, 1739. — While I was earnestly inviting all sinners to “enter into the holiest” by this “new and living way,”79 many of those that heard began to call upon God with strong cries and tears. Some sunk down, and there remained no strength in them; others exceedingly trembled and quaked: Some were torn with a kind of convulsive motion in every part of their bodies, and that so violently, that often four or five persons could not hold one of them. (WJW1:3)
Overwhelming Power Of The Holy Spirit At Everton
May 30, 1759. — Being with Mr. B——ll at Everton, I was much fatigued and did not rise. But Mr. B. did, and observed several fainting and crying out while Mr. B—— e was preaching. Afterward, at church, I heard many cry out, especially children, whose agonies were amazing: One of the eldest, a girl ten or twelve years old, was full in my view, in violent contortions of body, and weeping aloud, . (WJW2:11)
Just some examples from John Wesley's own Writings that help to later spur on the Pentecostal Movement!