What is the intended meaning of "those who are restricted"?

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

1. They are the people of al-Ṣuffah who devoted themselves to obedience to Allah and had nothing. [Ibn ʿAbbās, Muqātil]
2. They are the poor among the Muhājirūn. [Mujāhid]
3. They are people who devoted themselves to jihād and were unable to earn a livelihood. [Qatādah]
4. They are people who were injured while with the Prophet (ﷺ) and became incapacitated. [Saʿīd ibn Jubayr, al-Kisāʾī]