قُلْ بِفَضْلِ اللَّهِ وَبِرَحْمَتِهِ فَبِذَلِكَ فَلْيَفْرَحُوا هُوَ خَيْرٌ مِمَّا يَجْمَعُونَ ﴿۵۸﴾ قُلْ أَرَأَيْتُمْ مَا أَنْزَلَ اللَّهُ لَكُمْ مِنْ رِزْقٍ فَجَعَلْتُمْ مِنْهُ حَرَامًا وَحَلَالًا قُلْ آللَّهُ أَذِنَ لَكُمْ أَمْ عَلَى اللَّهِ تَفْتَرُونَ ﴿۵۹﴾

﴾58﴿ Qul bi fadlil laahi wa bi rahmatihee fa bi zaalika fal yafrahoo huwa khairun mimmaa yajma'oon
﴾59﴿ Qul ara'aitum maaa anzalal laahu lakum mir rizqin faja'altum minhu haraamanw wa halaalan qul aaallaahu azina lakum; am 'alal laahi taftaroon

﴾58﴿ Say, by the grace of Allah and His mercy, so in this let the people rejoice; it is better than what they accumulate (of worldly wealth)
﴾59﴿ Say, Have you thought about what Allah has provided for you as lawful sustenance, Then you make some of it unlawful and some of it lawful. Say, 'Has Allah permitted you to do so, or are you fabricating lies against Allah

[58] This verse is also an encouragement toward the Qur’an.
(فَبِذَلِكَ) – refers to the combined meaning of Allah’s grace and mercy. There is elliptical structure (ikhtisār) in the phrasing. The complete form would be: (فَبِذَلِكَ فَلْيَفْرَحُوا يَفْرَحُوا بِذَلِكَ) – and the repetition emphasizes the intensity of joy and the importance of what is being commanded.
The “grace (فضل)” of Allah refers to the Qur’an. The “mercy (رحمة)” refers to Tawḥīd (monotheism) and the Sunnah. These two are the true causes of joy for the believers.
This is why in a hadith, the Messenger of Allah (peace and blessings be upon him) said: "Whoever Allah guides to Islam and grants him knowledge of the Qur’an, but then he complains to creation about his hunger, Allah will write poverty between his eyes until death."
There are other interpretations as well: According to one opinion, the Qur’an is Allah’s grace, and His mercy is that He makes someone among the people of the Qur’an. A third opinion says: the Qur’an is the grace, and the Sunnah is the mercy.
In all cases, the central message is: true joy and pride should be in the blessings of guidance, not in worldly gain.
[59] In this verse, there is a refutation of active shirk (shirk fi‘lī). The message is: since the proofs of Tawḥīd have been clearly explained and the Qur’an is present, then why do you create your own rulings of ḥalāl and ḥarām?
(رِزْقٍ) – refers to provisions such as crops, livestock, etc., all of which come through the blessings of the heavens—that is why the word (أَنزَلَ) (sent down) is used.
This verse strongly refutes those who, without divine revelation, make halal and haram rulings by following others. Such behavior is referred to as: Shirk in legislation (شرک فی التشریع) Shirk in judgment (شرک فی الحکم) Shirk in declaring lawful and unlawful (شرک فی التحلیل والتحریم)
In essence, declaring something halal or haram without revelation is giving others a share in Allah’s exclusive right—and that is a form of shirk.