Charles Ellicott Commentary Exodus 16:2

"And the whole congregation of the children of Israel murmured against Moses and against Aaron in the wilderness:" — Exodus 16:2 (ASV)

The whole congregation ... murmured. —This is the third “murmuring.” The first was at Pi-hahiroth, on the appearance of the host of Pharaoh (Exodus 14:11–12); the second was at Marah, when the water proved undrinkable (Exodus 15:24); the third, in the wilderness of Sin, was brought about by no special occurrence—unless it were the exhaustion of the supplies of grain which had been brought out of Egypt—but seems to have resulted from a general dissatisfaction with the conditions of life in the wilderness, and with the prospects which lay before them.