Charles H. Spurgeon on Psalms 116:18

I will pay my vows unto the Lord now in the presence of all his people. He repeats the declaration. A good thing is worth saying twice. He thus stirs himself up to greater heartiness, earnestness, and diligence in keeping his vow, —really paying it at the very moment that he is declaring his resolution to do so. The mercy came in secret, but the praise is rendered in public; the company was, however, select; he did not cast his pearls before swine, but delivered his testimony before those who could understand and appreciate it.