Jesus spoke against outward acts of piety and religion, and pointed to the relationship that God desires to have with us based on love. God’s love shown to us in Jesus Christ is what allows us to love God and to love others.
The widow at Zarephath didn’t have anything, but gave anyways because she realized that she did have something to give, but it meant giving everything. We tend to hold tightly onto what we have, especially in times of trouble. We think about what we can give out of our things. God, however, gives all and desires all.