LEV556 It is far better and more positive to let the anger out rather than to harbor it inside and let it seethe and fester. Thus, a Jew is not permitted to hate a person in his heart, but should confront the person in as nice and non-angry fashion as possible, as discussed above [this verse]. Finally, Maimonides, who was careful and exacting in every word he wrote, does write that sometimes- if the issue is a very grave and large one-it is proper to get angry, but only once in a while, so that this emotion never becomes habitual.