Psalms 40:8

I delight to do thy will, O my God
This he came down from heaven to do, and this he did do, by preaching the Gospel, and working miracles; and above all by obtaining eternal redemption for his people, which he effected by fulfilling the law, becoming a sacrifice, and suffering and dying in their room; all which were the will of God, and grateful to him, and in doing which Christ took the utmost delight and pleasure, ( John 4:34 ) ( Luke 12:50 ) ;

yea, thy law [is] within my heart;
either the whole moral law, under which he was, as man, and the surety of his people; and which was written upon his heart, and which he perfectly obeyed; or that particular law, injunction, and command laid upon him by his Father, to offer himself a sacrifice, and lay down his life for men; which he agreed to, had it in his mind, his heart was set upon it, and he cheerfully complied with it, ( John 10:18 ) ( 14:31 ) .