LEV631 It is forbidden to be obdurate and not allow oneself to be appeased. On the contrary, one should be easily pacified and difficult to anger. Moreover, when asked by an offender for forgiveness, one should forgive with a sincere mind and a willing spirit. Even if one had been much vexed and grievously wronged, he is not to avenge nor bear a grudge (this verse). (From Maimonides, Mishneh Torah, "Laws of Return" 1:10).