James 4:17

To him, therefore, who knoweth how to be doing, a right thing, and is not doing it, it is, sin, unto him.

John 9:41

Jesus said unto them - If, blind, ye had been, ye had not had sin; but, now, ye say, We see, your sin, abideth.

Luke 12:47-48

And, that servant, who had come to know the will of his lord, and neither prepared, nor wrought unto his will, shall be beaten with many stripes;

John 13:17

If, these things, ye know, happy, are ye, if ye be doing them.

John 15:22

Had I not come and spoken unto them, Sin, had they none; but, now, have they no, excuse, for their sin.

Romans 1:20-21

For, the unseen things of him, from a world's creation, by the things made, being perceived, are clearly seen, even his eternal power and divinity, - to the end they should be without excuse;

Romans 1:32

Who, indeed, having acknowledged the righteous sentence of God, - that, they who such things as these do practise, are worthy of death, not only, the same things, are doing, but are even delighting together with them who are practising them .

Romans 2:17-23

If, however, thou, art taking the name of Jew, and resting thyself upon law, and boasting in God,

Romans 7:13

Did, then, that which is good, unto me become death? Far be it! But it was sin, that it might appear sin, through that which was good unto me working out death, in order that, exceeding sinful, might sin become through the commandment.

2 Peter 2:21

For, better, had it been for them - not to have obtained a personal knowledge of the way of righteousness, than, having obtained such knowledge, to turn back out of the holy commandment delivered unto them.

Treasury of Scripture Knowledge

Summary

Therefore to him that knoweth to do good, and doeth it not, to him it is sin.

Bible References

General references

Luke 12:47
And, that servant, who had come to know the will of his lord, and neither prepared, nor wrought unto his will, shall be beaten with many stripes;
John 9:41
Jesus said unto them - If, blind, ye had been, ye had not had sin; but, now, ye say, We see, your sin, abideth.
John 13:17
If, these things, ye know, happy, are ye, if ye be doing them.
John 15:22
Had I not come and spoken unto them, Sin, had they none; but, now, have they no, excuse, for their sin.
Romans 1:20
For, the unseen things of him, from a world's creation, by the things made, being perceived, are clearly seen, even his eternal power and divinity, - to the end they should be without excuse;
Romans 2:17
If, however, thou, art taking the name of Jew, and resting thyself upon law, and boasting in God,
Romans 7:13
Did, then, that which is good, unto me become death? Far be it! But it was sin, that it might appear sin, through that which was good unto me working out death, in order that, exceeding sinful, might sin become through the commandment.