What are the basics of economy in Islam

Q 1: Is it permissible to make oaths while buying and selling if one is truthful?

A: Making oaths in buying and selling is Makruh (disliked) in general, whether one is truthful or not. If a person lies in his oath then it is Makruh in the sense of being Haram (forbidden); the sin is greater and the punishment is more severe because it is a false oath. Even if it is a means of selling the product, it erases the blessings of the sale and profit. This is indicated by the Hadith narrated by Abu Hurayrah (may Allah be pleased with him), who said: I heard the Messenger of Allah (peace be upon him) saying: An oath may sell the product but erase the blessing. (Related by Al-Bukhari and Muslim in their Sahihs (authentic) Books of Hadith). (Part No. 13; Page No. 9) The wording here is that of Al-Bukhari. See Fat-h Al-Bari, Vol. 4, p.315. It was narrated also on the authority of Abu Dhar (may Allah be pleased with him) that the Prophet (peace be upon him) said: There are three to whom Allah will neither speak on the Day of Resurrection nor will look at them nor purify them (of their sins), and they will be severely tormented. When he repeated this (statement) thrice, Abu Dhar (may Allah be pleased with him) said: They are doomed and destroyed! (But) who are they, O Messenger of Allah?' He (peace be upon him) said: One whose lower garment trails, one who boasts of his favors done to others; and one who promotes sale of his business by making false oaths. (Related by Muslim in his Sahih, Vol.1, p.102). A similar report was narrated by Imam Ahmad in his Musnad. However, if the oath in buying and selling is truthful, then it is Makruh in the sense of being discouraged, for it means that he is promoting his product and encouraging the buyer to buy it by means of swearing an oath repeatedly while Allah (Exalted be He) says: Verily, those who purchase a small gain at the cost of Allâh’s Covenant and their oaths, they shall have no portion in the Hereafter (Paradise). Neither will Allâh speak to them, nor look at them on the Day of Resurrection, nor will He purify them, and they shall have a painful torment. Allah (Exalted be He) also says: And protect your oaths (i.e. do not swear much). And: And make not Allâh’s (Name) an excuse in your oaths against your doing good and acting piously (Part No. 13; Page No. 10) Also because of the general meaning of the Hadith narrated by Abu Qatadah Al-Ansary Al-Sulamy who said that he heard the Messenger of Allah (peace be upon him) saying: Beware of swearing too much when selling, for it sells (the product) then it erases (the blessing). (Related by Muslim in his Sahih, Ahmad in his Musnad, Al-Nasa'y, Ibn Majah and Abu Dawud). May Allah grant us success. May peace and blessings of Allah be upon our Prophet Muhammad, his family and Companions.