What is the disbelief in blessings (kufr al-ni'mah) and the gratitude for them (shukrha), and what is the punishment for the one who disbelieves in them?

Disbelief in blessings (kufr al-ni'mah) is to deny them and not show gratitude for them. Gratitude is expressed through the heart, tongue, and limbs, and by not using blessings in ways that displease Allah. The punishment for disbelief in blessings is their removal and a penalty for it. Just as gratitude increases blessings, disbelief in them removes them, as Allah Almighty says: "If you are grateful, I will surely increase you [in favor]; but if you deny, indeed, My punishment is severe."