It is narrated from Imam sadeq (AS) who narrated from the Prophet of Islam (PBUH) who said:
The three superior good deeds are: Treat people with fairness, and help the Muslim brothers/sisters for the sake of Allah (SWT), and remember Allah (SWT) in any condition [1].
[1] Al-Khisal, Page 121.
Source: en.shafaqna.com