Luke 12:10

And every man who will speak a word against the Son of man, it will be forgiven him, but to him who blasphemed against the Holy Spirit it will not be forgiven.

Matthew 12:31-32

Because of this I say to you, every sin and blasphemy will be forgiven to men, but the blasphemy of the spirit will not be forgiven men.

1 John 5:16

If any man may see his brother sinning a sin not toward death, he will ask, and he will give life to him, to those not sinning toward death. There is sin toward death. I do not say that he should make request about that.

1 Timothy 1:13

the man who was formerly blasphemous, and a persecutor, and an aggressor. But I obtained mercy because I did it being ignorant in unbelief.

Mark 3:28-30

Truly I say to you, that all the sins will be forgiven the sons of men, and the blasphemies, as many as they may blaspheme.

Luke 23:34

And Jesus said, Father, forgive them, for they know not what they are doing. And dividing his garments, they cast a lot.

Hebrews 6:4-8

For it is impossible for those who were once enlightened, and who tasted of the heavenly gift, and who became partakers of Holy Spirit,

Hebrews 10:26-31

For when we sin willfully after taking the knowledge of the truth, there remains 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 are doing. And dividing his garments, they cast a lot.
Matthew 12:31
Because of this I say to you, every sin and blasphemy will be forgiven to men, but the blasphemy of the spirit will not be forgiven men.
Mark 3:28
Truly I say to you, that all the sins will be forgiven the sons of men, and the blasphemies, as many as they may blaspheme.
1 Timothy 1:13
the man who was formerly blasphemous, and a persecutor, and an aggressor. But I obtained mercy because I did it being ignorant in unbelief.
Hebrews 6:4
For it is impossible for those who were once enlightened, and who tasted of the heavenly gift, and who became partakers of Holy Spirit,
Hebrews 10:26
For when we sin willfully after taking the knowledge of the truth, there remains no more a sacrifice for sins,
1 John 5:16
If any man may see his brother sinning a sin not toward death, he will ask, and he will give life to him, to those not sinning toward death. There is sin toward death. I do not say that he should make request about that.