From http://www.bible.ca/tongues-slain-in-spirit.htm come the following scriptures, which the website says charismatics use to prove the biblical basis of being slain in the Spirit.
II CHRONICLES 5:11-14 - And it came to pass, when the priests were come out of the holy [place]: (for all the priests [that were] present were sanctified, [and] did not [then] wait by course: Also the Levites [which were] the singers, all of them of Asaph, of Heman, of Jeduthun, with their sons and their brethren, [being] arrayed in white linen, having cymbals and psalteries and harps, stood at the east end of the altar, and with them an hundred and twenty priests sounding with trumpets:) It came even to pass, as the trumpeters and singers [were] as one, to make one sound to be heard in praising and thanking the LORD; and when they lifted up [their] voice with the trumpets and cymbals and instruments of musick, and praised the LORD, [saying], For [he is] good; for his mercy [endureth] for ever: that [then] the house was filled with a cloud, [even] the house of the LORD; So that the priests could not stand to minister by reason of the cloud: for the glory of the LORD had filled the house of God.
MATTHEW 17:5-7: While he yet spake, behold, a bright cloud overshadowed them: and behold a voice out of the cloud, which said, This is my beloved Son, in whom I am well pleased; hear ye him. And when the disciples heard [it], they fell on their face, and were sore afraid. And Jesus came and touched them, and said, Arise, and be not afraid.
JOHN 18:5-6: They answered him, Jesus of Nazareth. Jesus saith unto them, I am [he]. And Judas also, which betrayed him, stood with them. As soon then as he had said unto them, I am [he], they went backward, and fell to the ground.
ACTS 9:3-4: And as he journeyed, he came near Damascus: and suddenly there shined round about him a light from heaven: And he fell to the earth, and heard a voice saying unto him, Saul, Saul, why persecutest thou me?
This is what the author of the article, "Slain in the Spirit?", says on the website (in a slightly edited version) regarding these four Bible passages:
None of the above texts resemble anything remotely close to what happens when believers are slain in the spirit today. In 30 years of combined charismatic experience, my wife and I have observed fewer than 10 people fall, with no human instigation, under the power [of the Holy Spirit]. When people get slain it is due to the direct instigation of another person, not a sovereign act of God, as we see in 2 Chronicles 5:11-14. Invariably, charismatic people fall down when hands are laid on them. There are no examples in the Bible of people falling down when hands were laid on them.
The author goes on to say,
[In the Chronicles passage,] all the priests fell down, not just some. There is no record of a Pentecostal or charismatic service where all the people fell down simultaneously under the power of God. Keep in mind, the number of priests at the dedication numbered in the hundreds, and all of them had the exact same experience.
The following is my paraphrase of the author: In the Matthew passage, the disciples were not slain in the Spirit, but they were very much afraid; so much so, they fell on their faces (and not backward when someone touched them on the forehead!).
And an exact quotation of the author, with his emphasis:
This text [regarding Paul's conversion experience on the road to Damascus] cannot legitimately be used to prove the machinations taking place in charismatic circles. No one laid hands on Paul. According to the Biblical record this was not a regular occurrence in his life or ministry. Paul himself never testifies to laying hands on anyone and having them slain in the spirit, nor do any of the other writes of the New Testament, or Old Testament for that matter. Paul never lost consciousness, his faculties were very sharp, he was able to speak, he rationally answered the Lord
Finally, the author cites John White, who used the following two verses in his book When The Spirit Comes With Power to justify falling down under the Holy Spirit's power:
Daniel 10:9-10 But the sound of his words came to my ears, and on hearing his voice I went into a deep sleep with my face to the earth. Then a hand gave me a touch, awaking me, and putting me on my knees and my hands.
Rev. 1:17 - And when I saw him, I went down on my face at his feet as one dead. And he put his right hand on me, saying, Have no fear; I am the first and the last and the Living one.
And here is what the author says (with only minor changes by me) about White's use of these verses to prove the biblical nature of being slain in the Spirit:
In the event in Daniel we encounter the writing prophet at the banks of the Tigris. He alone sees the angelic being who has come to deliver to Daniel a sweeping revelation concerning the prophetic economy of God. This Old Testament account is totally devoid of any comparison of what takes place in Pentecostalism. First, Daniel was a writing prophet and as such the Lord manifested His Word to those prophets in various ways (dreams, visions, divine appearances, etc.).
Second, Daniel's experience was unexpected, whereas people fully expect to be slain in the spirit. The purpose of the manifestation to Daniel was to reveal a significant prophetic word to God's prophet. Next, while Daniel was overcome the angel touched him and gave him strength. This is something we do not see in today's services. I have seen multitudes fall, but none received supernatural strength. Notice also that Daniel fell face forward, whereas almost one hundred percent of charismatics who are slain in the Spirit fall backward; hence the need for catchers, since it is very difficult to catch people who are falling forward. It is interesting to note that in the biblical accounts when people have fallen, it is the sinners who fall backwards (John. 18:6). There simply is no legitimate manner in which this verse can be used to shore up a doctrine of being slain in the Spirit.
The text in Revelation 1:17, when examined, also fails to meet the test. John the beloved was an apostle of the Lamb. There are no more apostles today. Second, the reason John fell was because he saw his resurrected Lord. The purpose for the Lord Jesus appearing to John was to give him the final installment of the canon of Scripture. John was given a revelation of immense importance, but he never lost consciousness. Moreover, he also fell face forward.