He who gathers in summer is a prudent son,
but he who sleeps in harvest is a son who brings shame.

via Passage: Proverbs 10 (ESV Bible Online).

Why shame? Why not hunger?

Perhaps because the family must look for help to get the job done. Or worse, maybe they will need to ask others to help them out with shortages because the field was not completely harvested.

The Bible tells people to help the poor but it never gives you the idea that the poor are going to be happy about it.  And if they can think of themselves as ultimately responsible for needing to ask for help, it will be that much worse.