Obligation to the Community

If I am not for myself, who will be for me? But if I am only for myself, what am I? And if not now, when?

Hillel said: Do not withdraw from the community. And do not trust in yourself until the day of your death. And do not judge your fellow until you have put yourself in his place. Do not say something which cannot be heard (on the assumption) that eventually it will be heard. And do not say, 'When I have time I shall study,' perchance you will never have time. [AJWS translation]