Hawzah News Agency – The commander of the faithful, Imam Ali peace be upon him says:

أشكَرُ الناسِ أقنَعُهُم، وأكفَرُهُم لِلنِّعَمِ أجشَعُهُم.

'The most thankful of people are the most content, and the most ungrateful for blessings are the greediest.'

Source: Bihar al-Anwar, v. 77, p. 422, no. 40