Parashat Beshalach tells the story of the manna – the food on which the Israelites survived during their wilderness years. God spoke to Moses saying, "I will rain down bread from Heaven for you. The people are to go out each day and gather enough for that day. In this way I will test them and see whether they will follow my instructions.” (Shemot 16:4)
One common understanding of the manna is that there was just enough for every day, and on the sixth day – Friday – there was a double portion so the Israelites would have sufficient supplies going into Shabbat and would have no need to gather on Shabbat.
Included in the verse is the indication that God was somehow testing the Israelites. How was this a test and why?