He was quoting from the letter of St James in the bible, as follows.
"Take the case, my brothers of someone who has never done a single good act but claims that he has faith. Will that faith save him? If one of the brothers or one of the sisters is in need of clothes and has not enough food to live on, and one of you says to them, ‘I wish you well; keep yourself warm and eat plenty’, without giving them these bare necessities of llife, then what good is that?: if good works do not go with it, it is quite dead.
This is the way to talk to people of that kind:'You say you have faith and I have good deeds; I will prove to you that I have faith by showing you my good deeds–now you prove to me that you have faith without any good deeds to show.
You believe in one God–that is creditable enough, but the demons have the same belief, and they tremble with fear. Do realise, you senseless man, that faith without works is useless. You surely know that Abraham our Father was justified by his deed, because he offered Isaac on the altar? There you see it; faith and good deeds were working together; his faith became perfect by what he did This is what scripture really means when it says: Abraham put his faith in God, and this was counted as makinh him justified; and that is why he was called the friend of God
You see now that it is by doing something good, and not only by believing, that a man is justified." [James 2: 14-24]