The principle of sacrificial giving is found in the story of the widow’s offering that amounted to all she had. Jesus used her example saying,
“Truly I tell you, this poor widow has put in more than all those who are contributing to the treasury. For all of them have contributed out of their abundance; but she out of her poverty has put everything she had, all she had to live on” (Mk 12:41-44).
There is a great difference between the contribution of the rich and the commitment of this poor widow. For the rich, it costs them nothing, in that it was of no great consequence to give that for which they didn’t need to exist and depend on God. The poor woman did not hold back all she had to survive on, with the knowledge that God will ultimately take care of her every need. By faith, we give sacrificially of what we have in order to fully depend upon God for our daily bread (Mt 6:8,11, 25-34; Phil4:19). Why should the widow selfishly hold on to her last two copper coins and still struggle (what difference could two copper coins make?), rather than trust God with empty hands that He can fill with her needs as she thrives by daily depending on Him?
We also need to be mindful that Jesus gave Himself as the prime example of giving, “For you know the generous act of our Lord Jesus Christ, that though he was rich, yet for your sakes he became poor, so that by his poverty you might become rich” (2 Cor 8:9).