Augustine of Hippo
Catena Aurea · Johannesevangelium 6
Then said they unto him, What shall we do, that we might work the works of God? Jesus answered and said unto them, This is the work of God, that ye believe on him whom he hath sent. They said therefore unto him, What sign shewest thou then, that we may see, and believe thee? what dost thou work? Our fathers did eat manna in the desert; as it is written, He gave them bread from heaven to eat. Then said Jesus unto them, Verily, verily, I say unto you, Moses gave you not that bread from heaven; but my Father giveth you the true bread from heaven. For the bread of God is he which cometh down from heaven, and giveth life unto the world. Then said they unto him, Lord, evermore give us this bread.
(Tr. xxv. in Joan) He does not say, That ye believe Him, but, that ye believe on Him. For the devils believed Him, and did not believe on Him; and we believe Paul, but do not believe on Paul. To believe on Him is believing to love, believing to honour Him, believing to go unto Him, and be made members incorporate of His Body. The faith, which God requires of us, is that which worketh by love. Faith indeed is distinguished from works by the Apostle, who says, That man is justified by faith without the deeds of the law. (Rom. 3:28) But the works indeed which appear good, without faith in Christ, are not really so, not being referred to that end, which makes them good. For Christ is the end of the law for righteousness to every one that believeth (Rom. 10:4). And therefore our Lord would not separate faith from works, but said that faith itself was the doing the work of God; He saith not, This is your work, but, This is the work of God, that ye believe on Him: in order that he that glorieth might glory in the Lord.