A Buddhist encounters a sickly man who is living in poverty. The Buddhist takes the man into his own home feeds him and helps him recover from his illness. Which concept of Buddhism do the Buddhist's?

Oh, dude, that's like the ultimate good karma move right there! So, the Buddhist is totally embodying the concept of "mettā" which is all about loving-kindness and compassion towards others. It's like, the Buddhist is just being a solid dude and spreading those good vibes, you know?