"if man does not work, he ought not to eat. Every one is to work with his own hands, and what is more, every one's work is to produce something good"

Lewis is likely thinking of the following passages here.

2 Thessalonians 3:10 (KJV):"For even when we were with you, this we commanded you, that if any would not work, neither should he eat."

1 Thessalonians 4:11-12 (KJV): "And that ye study to be quiet, and to do your own business, and to work with your own hands, as we commanded you; That ye may walk honestly toward them that are without, and that ye may have lack of nothing."

1 Corinthians 3:13-15 (KJV): "Every man's work shall be made manifest: for the day shall declare it, because it shall be revealed by fire; and the fire shall try every man's work of what sort it is. If any man's work abide which he hath built thereupon, he shall receive a reward. If any man's work shall be burned, he shall suffer loss: but he himself shall be saved; yet so as by fire.