Verses with the word murmuring in the New Testament (2 verses):

John 7:12
And there was much murmuring among the people concerning him: for some said, He is a good man: others said, Nay; but he deceiveth the people.

Acts 6:1
And in those days, when the number of the disciples was multiplied, there arose a murmuring of the Grecians against the Hebrews, because their widows were neglected in the daily ministration.