Shukr is to recognise a blessing, turn to its Giver, and use it rightly; its opposite is ingratitude (kufrān).
Gratitude increases
- "If you are grateful, I will surely increase you; if you are ungrateful, My punishment is severe." (14:7)
Remember and give thanks
- "Remember Me and I will remember you; be grateful to Me and do not deny Me." (2:152)
Blessings beyond counting
- "If you tried to count God's blessings, you could not number them." (16:18) — gratitude is humility before this boundless grace.
Source: Qur'anic verses (M. Okuyan meal). Presented with a text/interpretation distinction.