Luke 12:10

And every one who shall speak a word against the Son of man, it shall be forgiven him: but unto him that blasphemeth against the Holy Spirit it shall not be forgiven.

Matthew 12:31-32

Therefore I say unto you, Every sin and blasphemy shall be forgiven unto men; but the blasphemy against the Spirit shall not be forgiven.

1 John 5:16

If any man see his brother sinning a sin not unto death, he shall ask, and God will give him life for them that sin not unto death. There is a sin unto death: not concerning this do I say that he should make request.

1 Timothy 1:13

though I was before a blasphemer, and a persecutor, and injurious: howbeit I obtained mercy, because I did it ignorantly in unbelief;

Mark 3:28-30

Verily I say unto you, All their sins shall be forgiven unto the sons of men, and their blasphemies wherewith soever they shall blaspheme:

Luke 23:34

And Jesus said, Father, forgive them; for they know not what they do. And parting his garments among them, they cast lots.

Hebrews 6:4-8

For as touching those who were once enlightened and tasted of the heavenly gift, and were made partakers of the Holy Spirit,

Hebrews 10:26-31

For if we sin wilfully after that we have received the knowledge of the truth, there remaineth no more a sacrifice for sins,

Treasury of Scripture Knowledge

Summary

And whosoever shall speak a word against the Son of man, it shall be forgiven him: but unto him that blasphemeth against the Holy Ghost it shall not be forgiven.

Bible References

General references

Luke 23:34
And Jesus said, Father, forgive them; for they know not what they do. And parting his garments among them, they cast lots.
Matthew 12:31
Therefore I say unto you, Every sin and blasphemy shall be forgiven unto men; but the blasphemy against the Spirit shall not be forgiven.
Mark 3:28
Verily I say unto you, All their sins shall be forgiven unto the sons of men, and their blasphemies wherewith soever they shall blaspheme:
1 Timothy 1:13
though I was before a blasphemer, and a persecutor, and injurious: howbeit I obtained mercy, because I did it ignorantly in unbelief;
Hebrews 6:4
For as touching those who were once enlightened and tasted of the heavenly gift, and were made partakers of the Holy Spirit,
Hebrews 10:26
For if we sin wilfully after that we have received the knowledge of the truth, there remaineth no more a sacrifice for sins,
1 John 5:16
If any man see his brother sinning a sin not unto death, he shall ask, and God will give him life for them that sin not unto death. There is a sin unto death: not concerning this do I say that he should make request.

American Standard Version Public Domain