Bukhari

Hadith Commentary:
In the Hereafter, there will be no share for them, nor will Allah speak to them, nor will He look at them with mercy.
And He will not purify them; rather, for them is a painful punishment.
It is understood from this that swearing a false oath by the name of Allah is among the gravest sins.
The scholars (ulama) have not liked swearing by the name of Allah even in a truthful matter, as a means of exalting (tanziyah) Him.
It is narrated in Musnad Ahmad that the Prophet (sallallahu alayhi wa sallam) said: The one who lets his lower garment (izar) hang below the ankles, the one who sells his goods by means of false oaths, and the one who reminds others of his favors—these are the criminals upon whom, on the Day of Resurrection, Allah will not look with mercy.
The purpose of Imam Bukhari rahimahullah in this chapter is to show that in trade, it is always necessary to uphold truthfulness.
Otherwise, a merchant who lies is considered a severe criminal in the sight of Allah.

Hadith Commentary:
(1)
A trader who sells his goods by swearing a false oath is in utter loss. According to the Qur'anic verse, such people will have no share in the Hereafter; on the Day of Resurrection, Allah will not speak to such people, nor will He look at them with mercy, nor will He purify them of their sins. Rather, for them there will be a painful punishment. In the hadith, it is mentioned that the Messenger of Allah (sallallahu alayhi wa sallam) said: "Three persons will be in loss on the Day of Resurrection: one who lets his garment hang below his ankles, the second who sells goods by swearing a false oath, and the third who reminds others of favors he has done for them." (Musnad Ahmad: 5/148)

(2)
Giving a false legal verdict (fatwa) in exchange for wealth, taking something from someone and then denying it, and swearing an oath in such matters—in short, all forms of dishonesty—fall under the application of the aforementioned verse.