They regulated this verse:
الرِّجَالُ قَوَّامُونَ عَلَى النِّسَاء بِمَا فَضَّلَ اللّهُ بَعْضَهُمْ عَلَى بَعْضٍ وَبِمَا أَنفَقُواْ مِنْ أَمْوَالِهِمْ فَالصَّالِحَاتُ قَانِتَاتٌ حَافِظَاتٌ لِّلْغَيْبِ بِمَا حَفِظَ اللّهُ وَاللاَّتِي تَخَافُونَ نُشُوزَهُنَّ فَعِظُوهُنَّ وَاهْجُرُوهُنَّ فِي الْمَضَاجِعِ وَاضْرِبُوهُنَّ فَإِنْ أَطَعْنَكُمْ فَلاَ تَبْغُواْ عَلَيْهِنَّ سَبِيلاً إِنَّ اللّهَ كَانَ عَلِيًّا كَبِيرًا {34}
Leaving obligation as a wife;
talk to her, if not work then separate bed, eventualy beat when all efforts apparently useless. For the beating not to make such excessive harm, it is required to regulate how to execute it. It is regulated as a means to give hard warning, avoiding injury.
This is an exercise in the nuances of the Arabic language:
The Arabic word used in verse 4:34 above is "idribuhunna", which is derived from "daraba" which means "beat". The thing with all of the Arabic words that are derived from the word "daraba" is that they don't necessarily mean "hit". The word "idribuhunna" for instance, could very well mean to "leave" them. It is exactly like telling someone to "beat it" or "drop it" in English.
The word "daraba" in verse 14:24 "Seest thou not how Allah sets (daraba) forth a parable? -- A goodly Word Like a goodly tree, Whose root is firmly fixed, And its branches (reach) To the heavens". "daraba" here meant "give an example". If I say in Arabic "daraba laka mathal", it means "give you an example".
The word "darabtum", which is derived from the word "daraba" in verse 4:94, which mean to "go abroad" :
"O ye who believe! When ye go abroad (darabtum) In the cause of Allah, Investigate carefully...
Hence it need not mean "beat" as in hit, but beat as in beat it for some time. (they are all in the same chapter).
The more accurate translation would be:
(4:34) [...]as for those women whose animosity or ill-will you have reason to fear, then leave them alone in bed, and then separate; and if thereupon they pay you heed, do not seek a way against them.
This is how this verse is interpreted by Islamic scholars.
This is corroborated by verses that forbid harsh treatment of wives:
"...Do not retain them (i.e., your wives) to harm them...(2:231)"
"If a wife fears cruelty or desertion on her husband's part, there is no blame on them if they arrange an amicable settlement between themselves; and such settlement is best; even though men's souls are swayed by greed. But if ye do good and practise self-restraint, God is well-acquainted with all that ye do. (4:128)"
Those who believe that this verse refers to wife beating are those who stop thinking at a place where the verse meets their expectations.