Is the hadith: "Leave people in their heedlessness; Allah provides for some of them through others" authentic, and what is the ruling on a person interfering between a seller and a buyer to advise one of them regarding the price?

The prohibition against a town dweller selling on behalf of a Bedouin (or, a resident selling for an outsider) has been reported. This occurs when a stranger arrives with goods, and the local resident says to him: "Leave it with me so I can sell it for you gradually at a higher price." This is forbidden if the person is aware of the prohibition and the goods are something the town needs. As for a person interfering between a buyer and a seller, it is not permissible due to the generality of the hadiths, unless there is significant harm or obvious deception, or if one of them seeks his advice, in which case he intervenes with counsel and consultation; for the Messenger of Allah, peace and blessings be upon him, said: "Religion is naseehah (sincere advice)."