exodus 16

Who are we? Moses says it twice to the Hebrews when they complained about not having food. Thinking about that phrase and the tendency for me to complain or criticise people/things, what right or authority do I have that puts me in the position to question what God is doing? Am I not just here to serve, to be a living sacrifice to Him? Who did the Hebrews think they were that they could grumble against God?