I thirst after thy precepts, and pursue them eagerly, as it were with open mouth, ready and greedy to receive them. It is a metaphor from one that makes great haste after another, whereby he is forced to pant and to open his mouth for air to refresh himself.
Related Commentaries of Psalms 119:131
Psalms 119:131
131 I opened my mouth, and panted: for I longed for thy commandments.