Bava Metzia

'Lend me a kor of wheat,' and stipulate a monetary return:  if it depreciates, he returns wheat; if it advances, he repays its value [as at the time of borrowing]. But did he not stipulate?  — R. Shesheth answered: It is thus meant: if no stipulation is made, and it depreciates, he takes wheat; if it advances, he repays its [original] value. MISHNAH. A MAN MAY NOT SAY TO HIS NEIGHBOUR, 'LEND ME A KOR OF WHEAT AND I WILL REPAY YOU AT HARVEST TIME;'  BUT HE MAY SAY, 'LEND ME UNTIL MY SON COMES, OR UNTIL I FIND THE KEY.'  HILLEL, HOWEVER, FORBADE [EVEN THIS.] AND THUS HILLEL USED TO SAY: A WOMAN MUST NOT LEND A LOAF TO HER NEIGHBOUR WITHOUT FIRST VALUING IT, LEST WHEAT ADVANCES AND THUS THEY [THE LENDER AND BORROWER] COME TO [TRANSGRESS THE PROHIBITION OF] USURY. GEMARA. R. Huna said: If he possesses a se'ah, he may borrow a se'ah; two se'ahs, he may borrow two se'ahs.  R. Isaac said: Even if he has only a se'ah, he may borrow many kors against it. R. Hiyya taught the following, which is in support of R. Isaac: [One may not borrow wine or oil for the same quantity to be returned, because] he has not a drop of wine or oil.  Surely then, if he has, he may borrow a large quantity against it. HILLEL, HOWEVER, FORBADE [EVEN THIS]. R. Nahman said in Samuel's name: The halachah agrees with Hillel's ruling. The law is nevertheless not in accordance with him. AND THUS HILLEL USED TO SAY, A WOMAN MUST NOT LEND, etc. Rab Judah said in Samuel's name: This is Hillel's view, but the Sages maintain, One may borrow and repay unconditionally. Rab Judah also said in Samuel's name: The members of a company who are particular with each other  transgress [the prohibition of] measure, weight, number, borrowing and repaying on the Festival,  and, according to Hillel, usury too. Rab Judah also said in Samuel's name: Scholars may borrow from each other on interest. Why? Fully knowing that usury is forbidden, they merely present gifts to each other.  Samuel said to Abbuha b. Ihi: Lend me a hundred peppercorns for a hundred and twenty. And this is well. Ran Judah said in Rab's name: One may lend to his sons and household on interest, in order to give them experience thereof.  This, nevertheless, is incorrect, because he will come to cling thereto. MISHNAH. A MAN MAY SAY TO HIS NEIGHBOUR, 'HELP ME TO WEED, AND I WILL HELP YOU; ASSIST ME TO HOE, AND I WILL ASSIST YOU.'  BUT HE MAY NOT SUGGEST, 'DO YOU WEED WITH ME, AND I WILL HOE WITH YOU; DO YOU HOE WITH ME, AND I WILL WEED WITH YOU.'