Peter takes the argument of what our Lord has done for us to show how we are to be as a corporate collaboration of people in Him.
Do not grumble, as in do not be complaining. Don't criticize, find fault, be irritable or argumentative, or whine to fellow believers-and definitely not to unbelievers.
Standing firm, which we can do all the way from sowing the right seed to receiving the greatest harvest of the highest quality.
Following Jesus' great message to the multitudes, He moves from the crowds to the ministering of the individual needs of people.