“[…] Give as gifts of mercy the things that are from within, and look! everything about you will be clean.”
~Luke 11:41

What are the things “from within?”
Jesus has been asked to dine with the Pharisees and has reprimanded them for outwardly appearing to be spiritual while hiding greediness and wickedness within. (Luke 11:39)
“The one who made the outside made also the inside, did he not?”
Jesus explains God’s justice and love, which we are capable of imitating, should be our main focus.
Then he further denounces their religious hypocrisy. (Luke 11:40,42,44)
So when Jesus says to give gifts from within, he appears to be alluding to sharing generously from a pure heart, with selfless motives.
The attitude with which we give stems, of course, from the way we choose to think. (Jer. 4:14)
At the end of the day, God is looking at whether or not our love is sincere. (1 Pet. 4:8,9)