I will run the way of thy commandments, I will obey thy precepts with all readiness, fervency, and diligence, when thou shalt enlarge my heart: either,
1. When thou shalt bring me out of my present straits or distresses. This in deed is called enlarging, as Psalms 4:1, Psalms 18:36, but never, to my remembrance, the enlarging of the heart. Or rather,
2. When thou shalt replenish my heart with more wisdom and love to and delight in thee and thy law; for this enlargement of heart in Scripture is ascribed to wisdom, 1 Kings 4:29, and love, 2 Corinthians 6:11, and joy, Isaiah 60:5; when thou shalt knock off those fetters of remaining corruption, and give me a more noble and generous disposition towards thee, and stablish me with thy free spirit, as it is expressed, Psalms 51:12. Thus David both owns his duty, and asserts the absolute necessity of God's grace to the performance of it.