John Calvin Commentary Psalms 119:131

"I opened wide my mouth, and panted; For I longed for thy commandments." — Psalms 119:131 (ASV)

I opened my mouth and panted. By these words, the Psalmist wants us to understand that he was inflamed with such love for and longing for the divine law, that he was unceasingly sighing for it. In comparing himself to those who are hungry, or to those who burn with parching thirst, he has used a very appropriate metaphor.

As such people indicate the vehemence of their desire by opening the mouth and by distressful panting, as if they would suck up the whole air, so too the Prophet affirms that he himself was oppressed with continual distress. The opening of the mouth, then, and the drawing of breath, are set in opposition to a cold assent to the word of God.

Here the Holy Spirit teaches with what earnestness of soul the knowledge of divine truth must be sought. Therefore, it follows that those who make little or no progress in God’s law are punished by their own indolence or carelessness. When David affirms that he panted continually, he points out not only his ardor but also his constancy.