28 Then said they unto him, What shall we do, that we might work the works of God? 29 Jesus answered and said unto them, This is the work of God, that ye believe on him whom he hath sent. (John 6:28-29 KJV)
William Burkitt’s Commentary
Here the Jews, who were strict observers of the ceremonial law of Moses, and rested thereupon for salvation, inquire of our Saviour what they should do that they might please God? Christ directs them to the great duty of believing on himself to own and acknowledge him to be the true Messiah, and as such to rely upon him alone for salvation; This is the work of God, that ye believe, &c.
Learn hence, That for a penitent humble sinner to believe in the Lord Jesus Christ, is a work highly pleasing and acceptable unto God. Christ calls faith the work of God, upon a threefold account; it is the work of his efficiency and operation; it is the work of his commanding; and it is the work of his approbation and acceptation, a work that God is highly pleased with, and greatly delighted in; This is the work of God.