What is meant by "volunteers good of his own accord"?

Imām Ibn al-Jawzī (d. 597/1201) summarized the scholars' opinions in his book "Zād al-Masīr" as follows:

1. It means to feed two people rather than just one for each day. [Ibn ʿAbbās, Mujāhid]
2. It means feeding a number of people for each day. [Ṭāwūs]
3. It means giving more to the poor person than their need. [Reported from Mujāhid; Anas ibn Mālik did this when he grew old]