"But when you give to the needy, do not let your left hand know what your right hand is doing, so that your giving may be in secret." Matthew 6:3
"On the contrary: 'If your enemy is hungry, feed him; if he is thirsty, give him something to drink'..." Romans 12:20A
First mile giving requires us to be dutiful in our giving to follow what God requires. Second mile giving is about people seeing God's heart when we are generous, because we do not give out of requirement or reward. It's not about hiding giving— it's about living a life of gratitude, because of what God has given us.
