Verily, those who purchase a small gain at the cost of Allahs Covenant and their oaths, they shall have no portion in the Hereafter (Paradise)... (till) ... and they shall have a painful torment. (V.3 -77)

`Abdullah bin Masud said, "Allah's Messenger (ﷺ) said, 'Whoever takes an oath when asked to do so, in which he may deprive a Muslim of his property unlawfully, will meet Allah Who will be angry with him.' So Allah revealed in confirmation of this statement:--"Verily! Those who Purchase a small gain at the cost of Allah's Covenant and oaths, they shall have no portion in the Hereafter..." (3.77) Then entered Al-Ash'ath bin Qais and said, "What is Abu `Abdur-Rahman narrating to you?" We replied, 'So-and-so." Al-Ash'ath said, "This Verse was revealed in my connection. I had a well in the land of my cousin (and he denied my, possessing it). On that the Prophet (ﷺ) said to me, 'Either you bring forward a proof or he (i.e. your cousin) takes an oath (to confirm his claim)' I said, 'I am sure he would take a (false) oath, O Allah's Messenger (ﷺ).' He said, 'If somebody takes an oath when asked to do so through which he may deprive a Muslim of his property (unlawfully) and he is a liar in his oath, he will meet Allah Who will be angry with him.' "

A man displayed some merchandise in the market and took an oath that he had been offered a certain price for it while in fact he had not, in order to cheat a man from the Muslims. So then was revealed:-- "Verily! Those who purchase a small gain at the cost of Allah's Covenant and their oaths..."(3.77)

Two women were stitching shoes in a house or a room. Then one of them came out with an awl driven into her hand, and she sued the other for it. The case was brought before Ibn `Abbas, Ibn `Abbas said, "Allah's Messenger (ﷺ) said, 'If people were to be given what they claim (without proving their claim) the life and property of the nation would be lost.' Will you remind her (i.e. the defendant), of Allah and recite before her:--"Verily! Those who purchase a small gain at the cost of Allah's Covenant and their oaths..."(3.77) So they reminded her and she confessed. Ibn `Abbas then said, "The Prophet (ﷺ) said, 'The oath is to be taken by the defendant (in the absence of any proof against him).