Murmuring signifies the speaking against a person or thing, out of dislike, impatience, or discontent. It was a sin the Jews were very much guilty of, as may be read, Exo_15:24 16:7,8 17:3 Num_14:27 16:11,41. The apostle may either refer to all their murmurings, when he saith they
were (as the punishment of their sin) destroyed of the destroyer, or to that more universal murmuring upon the ill report the spies brought up of the land of Canaan, of which we read, Num_14:1-45.