Positive command to loan money to a needy Jew:
It is a positive Biblical command, for one who is able to afford it, to lend money to a Jew that is in need. This applies even if the borrower is wealthy and is simply in temporary need for the money.
How much must one lend the Jew? One must lend the Jew as much money as he requires for his living, if one is able to afford to lend this amount.
 Admur Halva 1