"Had Noah been part of Abraham's generation, he would not have been taken into account". Why is only Abraham mentioned, when one could also include Hanoch and Methuselah? In order to understand, we must distinguish between two types of tsaddikim. There are those who isolate themselves and do not involve themselves with other people, and there are those who are involved with others. Which are we to consider preferable? The commentators wrote that the involved one is preferable, despite the fact that the isolated one gains more in Torah and from sanctity and abstinence, which is not the case with a person involved with others. In the latter's case, the tzaddik's generation benefits from him…Hanoch and Methuselah were [righteous] only for themselves, while it says about Abraham "For I have known that he command his children and household after him to do charity and justice".