Exodus 16:28 - Ellicott's Commentary On The Whole Bible

How long refuse ye to keep my commandments ? — The people had already broken one of the positive precepts with respect to the manna (see Exodus 16:20); now they broke another — in the spirit, at any rate — since they would have gathered had they found anything to gather. Thus they provoked God a second time; yet was He “so merciful, that He destroyed them not,” but “turned His anger away, and did not stir up all His wrath” (Psalms 78:38). Apparently He made allowance for the ordinance being a new one, to which they were not yet accustomed.