Great has been my sin in taking the number of what is yours Lord

The sin of taking the number of the people of The Lord

Now Satan, designing evil against Israel, put into David’s mind the impulse to take the number of Israel.
1 Chronicles 21:1

Then David said to God, Great has been my sin in doing this; but now, be pleased to take away the sin of your servant, for I have done very foolishly.
1 Chronicles 21:8