Luke 13:24
"You must struggle on to get in through the narrow door, for I tell you, many will try to get in, but will not succeed,
Hebrews 4:11
So let us do our best to be admitted to that rest, so that not one of us may fail through the same sort of disobedience.
Hebrews 6:11-12
And we desire each one of you to continue to show the same earnestness to the very end, that you may enjoy your hope to the fullest,
2 Peter 1:5
Now for this very reason you must do your level best to supplement your faith with moral character, moral character with knowledge,
2 Peter 1:10
Therefore, brothers, be all the more in earnest to make certain to yourselves God's call and choice of you. For if you cultivate these qualities, you will never slip,