According to rahyafte (the missionaries and converts website):
One day, Imam Hasan was eating when a dog came and stood in front of the Imam. Imam, every bite he ate, he threw a bite in front of the dog. A man asked: “O son of the prophet Mohammad! “Let me take this animal away.”
Imam Hasan said : “ No , Don’t do that . I am ashamed of God that a living thing looks at my face and I am eating and not feeding him.”
