פנים יפות – Parshas Mishpatim

the Mechiltah says on this Posuk that the word "here does not mean, "if" that if one lends his fellow Yid, but rather that it is an obligation for one to loan money to his fellow Yid. The Torah does not command one to lend his utensils or other possessions, but only for one to lend his money. The reason for this is because when one lends money to another, he has no loss at all for the exact amount of money he lent, is the amount he will receive back. As opposed to when one lends his utensils or possessions, the wear and tear of the use by the borrower will decrease the value somewhat. Thus, when it is returned to the lender, he receives back something less than what he lent. Therefore, the Torah does not mandate that one lend possessions to another. It is up to the person to decide if he wants to lend his possessions knowing that when he gets it back, it will have a lower value than what he lent - the Torah does not obligate one to do so.

It says in Vayikra Rabbah 30:6 that when one takes a Lulav in his hands to be Mekayeim the Mitzvah, if it is a stolen Lulav, the Lulav screams out to Hashem and says, "I am stolen", and the Malachei Hashareis say, "Woe to this person who made his defender into his antagonizer." (Meaning that not only did he not get the Mitzvah of Lulav, but quite the opposite, he will be taken to task for stealing). According to this, the Torah tells us that the Lulay must be yours, and it cannot even be borrowed, for the Mitzvah of Lulav is to make Klal Yisroel be desired by Hakodosh Boruch Hu- by their Father in Heaven, and the Torah wants to make sure that there isn't even a hint of theft. If there is Chas V'sholom a hint of theft, it will not only be desired by Hakodosh Boruch Hu, but will be repudiated by Him.