Be ye angry and sin not (orgizesthe kai mē hamartanete). Permissive imperative, not a command to be angry. Prohibition against sinning as the peril in anger. Quotation from Psa 4:4.
Let not the sun go down upon your wrath (ho hēlios mē epiduetō epi parorgismōi). Danger in settled mood of anger. Parorgismos (provocation), from parorgizō, to exasperate to anger, occurs only in lxx and here in N.T.