A habit of hearty private prayer...

Of all the evidences of the real work of the Spirit, a habit of hearty private prayer is one of the most satisfactory that can be named. A man may preach from false motives. A man may write books and make fine speeches and seem diligent in good works, and yet be a Judas Iscariot. But a man seldom goes into his closet, and pours out his soul before God in secret, unless he is in earnest. The Lord himself has set his stamp on prayer as the best proof of true conversion.  -J.C. Ryle