What is meant by "their mark"?

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

1. Their appearance of dignity and beauty. [Ibn ʿAbbās]
2. Their humility. [Mujāhid]
3. The signs of poverty upon them. [Al-Suddī, Al-Rabīʿ ibn Anas]