Zayd ibn San'an narrates:
Once, God’s Messenger borrowed some money from me. I was not yet a Muslim then. I went to him to collect my debt before its due time, and insulted him, saying:
'You the children of 'Abd al-Muttalib, are very reluctant to pay your debts!'
Umar became very angry with this insult of mine and shouted:
'O enemy of God! Were it not for the treaty between us and the Jewish community, I would cut off your head! Speak to God’s Messenger politely!'
However, God’s Messenger smiled at me and, turning to Umar, said:
'Umar, pay the man his debt! And add to it the amount of twenty gallons because you have frightened him!'