He [also] used to say: If I am not for myself, who will be for me? But if I am for myself only, what am I? And if not now, when?
דתני רב יוסף (שמות כ"ב) אם כסף תלוה את עמי את העני עמך, עמי ונכרי - עמי קודם, עני ועשיר - עני קודם, ענייך ועניי עירך - ענייך קודמין, עניי עירך ועניי עיר אחרת - עניי עירך קודמין.
Babylonian Talmud, Baba Metzia 71a:3
R. Joseph learnt: If you lend money to any of my people that are poor with you: [this teaches, if the choice lies between] a Jew and a non-Jew, a Jew has preference; the poor or the rich the poor takes precedence; your poor [i.e. your relatives] and the [general] poor of your town, your poor come first; the poor of your city and the poor of another town the poor of your own town have prior rights. [Soncino translation]
Our Rabbis taught: We sustain the non-Jewish poor with the Jewish poor, visit the non-Jewish sick with the Jewish sick, and bury the non-Jewish dead with the Jewish dead, for the sake of peace. [AJWS translation]
[ה] "וכשלו איש באחיו"-- אינו אומר "איש באחיו" אלא בעון אחיו; מלמד שכל ישראל ערבים זה בזה.
5) (Vayikra 26:37) "And they will stumble, one man by his brother": It is not written "one man because of his brother" (i.e., in running), but "one man by his brother," the sin of his brother — whereby we are taught that all of Israel are responsible, one for the other.