To seem to be zealous, if it be not according to the word, is not obedience, but will-worship. The apostle condemns the worshipping of angels, which had a show of humility. Though we serve God with weakness, it may be with willingness. You love to see your servants go cheerfully about their work. Under the law, God will have a free-will offering.
Willingness is the soul of obedience.
God sometimes accepts of willingness without the work, but never of the work without willingness. Quae ebullit prae ardore . The glorious angels, who, for burning in fervour and devotion, are called seraphims, are chosen by God to serve him in heaven. The snail under the law was unclean, because a dull, slothful creature. Obedience without fervency, is like a sacrifice without fire.