Question: Some businessmen agree to sell merchandise, for example the price of the merchandise is five riyals, they all agree that it will be five riyals. So what is the ruling on this?
Answer: Agreeing to this is not allowed because the Prophet (ﷺ) said:
دَعُوا النَّاسَ يَرْزُقُ اللَّهُ بَعْضَهُمْ مِنْ بَعْضٍ
Leave the people alone and let Allah provide for them from one another
[Muslim no. 1522]
So it is not allowed to agree to raise the prices, rather it is not allowed for the state to agree to unify prices except in specific circumstances. Otherwise, it has come in a Saheeh Hadith that some of the Companions said: Oh Messenger of Allah! Fix the prices for us. He said:
إِنَّ اللَّهَ هُوَ الْمُسَعِّرُ
Allah is the one who fixes prices
[Saheeh Sunan Abu Dawood no. 3451]
So what does it concern you, if the businessmen agree to exploit the people and exaggerate in the prices of their merchandise.
[Taken from Fatawaa ar-Raaghib no. 6 found here: https://www.alalbany.net/3785 ] Translated by Faisal ibn Abdul Qaadir ibn Hassan