1. It is stated that the lender was Zaid bin Shu'bah Al-Kinani who had not yet embraced Islam and that accounts for his not showing due regard to the Prophet (PBUH), and for his being stern in his demand. The Prophet (PBUH) advised his Companions that it is well for the affluent to demand his loan in a polite manner; but if someone does not show politeness in it, his rudeness should be ignored because he who has a rightful claim, can tend to anger although he should not cross the limits laid down by Shari'ah in this respect.
2. At the time of repayment of loan, it is Mustahabb (desirable) for the debtor to pay with his own pleasure something more than due to the lender; but if the lender demands more, this extra money will be deemed interest Riba (or usury) which is neither lawful to receive nor to pay.