A companion of the Messenger of Allah (may Allah be pleased with him) narrates that the Messenger of Allah (peace and blessings be upon him) said: Leave people alone so that some may benefit from others; however, when someone seeks advice from another, he should give advice.
Hadith Takhrij«حديث صحيح لغيره، أخرجه البخاري في التاريخ الكبير : 3/ 15، (انظر مسند أحمد ترقيم الرسالة: 28282 ترقیم بيت الأفكار الدولية: 18471»
Brief Explanation
Benefits: … What is meant by leaving the people is that you should leave the sellers and buyers alone; they will make their transactions among themselves. Do not intervene by giving advice about prices or by acting as a broker. However, if someone seeks advice, then you should sincerely wish well for him, rising above personal interest.