Sahih International

And [remember] when your Lord proclaimed, 'If you are grateful, I will surely increase you [in favor]; but if you deny, indeed, My punishment is severe.' "

Tafsir al-Jalalayn
And when your Lord proclaimed, [when] He made it known that: “If you are thankful, for My graces, through affirmation of [My] Oneness and obedience [to Me], then assuredly I shall give you more; but if you are thankless, [if] you deny [the truth of] the grace, through disbelief and disobedience, then assuredly I shall chastise you — as is indicated by [His following words] — My chastisement is indeed severe” ’.