Adam Clarke on Nehemiah 5:13

Also I shook my lap - This was a significant action frequent among the Hebrews; and something of the same nature was practiced among other nations. "When the Roman ambassadors entered the senate of Carthage, they had their toga gathered up in their bosom. They said, We carry here peace and war; you may have which you will. The senate answered, You may give which you please. They then shook their toga, and said, We bring you war. To which all the senate answered, We cheerfully accept it." See Livy. lib. xxi., cap. 18; and see Calmet.