beshalach

The Posuk says 'ה told Moshe, I'm going to send down bread from heaven that the people should go out & collect everyday in order for me to test them to see if they will go in the ways of my Torah or not.
Rashi says that the test is to see if they will keep all the applicable laws of the מן, like not going to collect it on shabbos, or leaving any over until the next day.
Why couldn't they leave any over? And how is not leaving any over testing them to see if they'll keep the whole Torah?
The יעלת חן says we need to understand what the נסיון of the מן was, & how it's considered going in the way of Torah.
He explains that going in the way of the Torah means toiling & creating one's own insights in Torah. For if a person totally immerses himself in Torah, then it will be his lifeline. Like the Chachamim say, this is the way of Torah; eat bread & salt & minimize the comforts of this world, then you can grow in Torah. Toiling & forgoing comforts is not usually found in the wealthy, as it says, watch the children of the poor for Torah is likely to come from them.
Once the people had the מן, the challenge to keep the Torah was so much greater, for all their needs were taken care of. So the test was one of wealth; would they now be able to devote themselves completely to Torah?
The Mechilta says the Nisayon was a test for 'ה that anyone who serves 'ה with all his heart, 'ה will make sure he has all that he needs, just like he did for the ones who got the מן.
Maybe this is how we could understand what Rashi is telling us. If a person has total trust in 'ה & doesn't leave over any מן,by not worrying about tomorrow he proves that he trusts in 'ה & he will totally immerse himself in Torah. Then 'ה will take care of all his needs. If he still shows his commitment to Torah even after having everything he needs, that's passing the ultimate test of being like the ones who got the מן, who had everything & still committed themselves to 'ה & His Torah!