Luke 13:24
"Strain every nerve to force your way in through the narrow gate," He answered; "for multitudes, I tell you, will endeavour to find a way in and will not succeed.
Hebrews 4:11
Let it then be our earnest endeavour to be admitted to that rest, so that no one may perish through following the same example of unbelief.
Hebrews 6:11-12
But we long for each of you to continue to manifest the same earnestness, with a view to your enjoying fulness of hope to the very End;
2 Peter 1:5
But for this very reason--adding, on your part, all earnestness-- along with your faith, manifest also a noble character: along with a noble character, knowledge;
2 Peter 1:10
For this reason, brethren, be all the more in earnest to make sure that God has called you and chosen you; for it is certain that so long as you practise these things, you will never stumble.