Luke 12:10

Everyone also who says a word against the Son of man will be forgiven for it, but he who blasphemes against the holy Spirit will never be forgiven.

Matthew 12:31-32

I tell you therefore, men will be forgiven any sin and blasphemy, but they will not be forgiven for blaspheming the Spirit.

1 John 5:16

If anyone notices his brother committing a sin which is not deadly, he will ask and obtain life for him ??for anyone who does not commit a deadly sin. There is such a thing as deadly sin; I do not mean he is to pray for that.

1 Timothy 1:13

though I had formerly been a blasphemer and a persecutor and a wanton aggressor. I obtained mercy because in my unbelief I had acted out of ignorance;

Mark 3:28-30

I tell you truly, the sons of men shall be forgiven all their sins, and all the blasphemies they may utter,

Luke 23:34

Jesus said, "Father, forgive them, they do not know what they are doing." Then they distributed his clothes among themselves by drawing lots.

Hebrews 6:4-8

For in the case of people who have been once enlightened, who tasted the heavenly Gift, who participated in the holy Spirit,

Hebrews 10:26-31

For if we sin deliberately, after receiving the knowledge of the Truth, there is no longer any sacrifice for sins left,

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
Jesus said, "Father, forgive them, they do not know what they are doing." Then they distributed his clothes among themselves by drawing lots.
Matthew 12:31
I tell you therefore, men will be forgiven any sin and blasphemy, but they will not be forgiven for blaspheming the Spirit.
Mark 3:28
I tell you truly, the sons of men shall be forgiven all their sins, and all the blasphemies they may utter,
1 Timothy 1:13
though I had formerly been a blasphemer and a persecutor and a wanton aggressor. I obtained mercy because in my unbelief I had acted out of ignorance;
Hebrews 6:4
For in the case of people who have been once enlightened, who tasted the heavenly Gift, who participated in the holy Spirit,
Hebrews 10:26
For if we sin deliberately, after receiving the knowledge of the Truth, there is no longer any sacrifice for sins left,
1 John 5:16
If anyone notices his brother committing a sin which is not deadly, he will ask and obtain life for him ??for anyone who does not commit a deadly sin. There is such a thing as deadly sin; I do not mean he is to pray for that.