❶ It is narrated from Hazrat Salman (RA) that the Messenger of Allah ﷺ said:
ثلاثة لا ينظر الله إليهم يوم القيامة: أشيمط زان ، وعائل مستكبر ، ورجل جعل الله بضاعته لا يشترى إلا بيمينه ، ولا يبيع إلا بيمينه
"Three people are such that Allah Almighty will not look at them with mercy on the Day of Resurrection: an elderly adulterer, a proud poor person, and a man whom Allah has provided with goods, but he does not buy except by swearing an oath, nor does he sell except by swearing an oath."
[Ṣaḥīḥ: Ṣaḥīḥ al-Targhīb: 1788, Kitāb al-Buyūʿ: Bāb al-Targhīb al-Tujjār fī al-Ṣidq, narrated by al-Ṭabarānī in al-Kabīr]
❷ It is narrated from Hazrat Abu Hurairah (RA) that the Messenger of Allah ﷺ said:
أربعة يبغضهم الله: البياع الحلاف ، والفقير المختال ، والشيخ الزاني ، والإمام الجائر
"There are four people whom Allah Almighty hates: the merchant who swears oaths excessively in buying and selling, the arrogant poor person, the elderly adulterer, and the unjust ruler."
[Ṣaḥīḥ: Ṣaḥīḥ al-Targhīb: 1790, Kitāb al-Buyūʿ: Bāb al-Targhīb al-Tujjār fī al-Ṣidq, Nasā’ī: 5/86, Ibn Ḥibbān in his Ṣaḥīḥ: 5532]
❸ It is narrated from Hazrat Qatādah (RA) that the Messenger of Allah ﷺ said:
إياكم وكثرة الحلف فى البيع فإنه ينفق ، ثم يمحق
"Beware of excessive swearing in trade, for it may help sell the goods, but it removes the blessing."
[Muslim: 1607, Nasā’ī: 7/246, Ibn Mājah: 2209]
