قَدْ عَلِمْنَا مَا فَرَضْنَا عَلَيْهِمْ فِي أَزْوَاجِهِمْ
We know what We have prescribed for them concerning their wives. (Part of Qur'an 33:50)
The phrase is introduced in a discussion of taqdīr: how an obligation relates to a specified amount or limit. This leads to the legal debate on a minimum amount of mahr (dower).
Taqdīr means fixing an amount or boundary. The existence of an obligation and the precise minimum quantity of that obligation are separate issues. No precise numeral follows directly from this excerpt alone; jurists combine it with other evidence and legal reasoning.