Mark 9:39

"You should not have tried to hinder him," replied Jesus, "for there is no one who will use my name to perform a miracle and be able the next minute to speak evil of me.

Matthew 7:22-23

Many will say to me on that day, "'Master, Master, have we not prophesied in Thy name, and in Thy name expelled demons, and in Thy name performed many mighty works?'

Matthew 13:28-29

"'Some enemy has done this,' he said. "'Shall we go, and collect it?' the men inquire.

Mark 10:13-14

One day people were bringing young children to Jesus for Him to touch them, but the disciples interfered.

Acts 19:13-16

But there were also some wandering Jewish exorcists who undertook to invoke the name of Jesus over those who had the evil spirits, saying, "I command you by that Jesus whom Paul preaches."

1 Corinthians 9:27

but I hit hard and straight at my own body and lead it off into slavery, lest possibly, after I have been a herald to others, I should myself be rejected.

1 Corinthians 12:3

For this reason I would have you understand that no one speaking under the influence of The Spirit of God ever says, "Jesus is accursed," and that no one is able to say, "Jesus is Lord," except under the influence of the Holy Spirit.

1 Corinthians 13:1-2

If I can speak with the tongues of men and of angels, but am destitute of Love, I have but become a loud-sounding trumpet or a clanging cymbal.

Philippians 1:18

What does it matter, however? In any case Christ is preached--either perversely or in honest truth; and in that I rejoice, yes, and will rejoice.

Treasury of Scripture Knowledge

Summary

But Jesus said, Forbid him not: for there is no man which shall do a miracle in my name, that can lightly speak evil of me.

General references

Bible References

Forbid

Mark 10:13
One day people were bringing young children to Jesus for Him to touch them, but the disciples interfered.
Matthew 13:28
"'Some enemy has done this,' he said. "'Shall we go, and collect it?' the men inquire.
Philippians 1:18
What does it matter, however? In any case Christ is preached--either perversely or in honest truth; and in that I rejoice, yes, and will rejoice.

There

Matthew 7:22
Many will say to me on that day, "'Master, Master, have we not prophesied in Thy name, and in Thy name expelled demons, and in Thy name performed many mighty works?'
Acts 19:13
But there were also some wandering Jewish exorcists who undertook to invoke the name of Jesus over those who had the evil spirits, saying, "I command you by that Jesus whom Paul preaches."
1 Corinthians 9:27
but I hit hard and straight at my own body and lead it off into slavery, lest possibly, after I have been a herald to others, I should myself be rejected.
1 Corinthians 13:1
If I can speak with the tongues of men and of angels, but am destitute of Love, I have but become a loud-sounding trumpet or a clanging cymbal.

Lightly

1 Corinthians 12:3
For this reason I would have you understand that no one speaking under the influence of The Spirit of God ever says, "Jesus is accursed," and that no one is able to say, "Jesus is Lord," except under the influence of the Holy Spirit.

General references

2 Corinthians 13:8
For we have no power against the truth, but only for the furtherance of the truth;