'Earnest' in the Bible

All of these with one mind continued earnest in prayer, together with some women, and Mary the mother of Jesus, and His brothers.

They all paid [a great deal of] attention to him, from the least to the greatest, saying, “This man is what is called the Great Power of God!”

So Peter was kept in prison, but earnest prayer to God for him was being offered by the assembly.

This too is my own earnest endeavour--always to have a clear conscience in relation to God and man.