"Beware of swearing oaths when selling, for it may help you to make a sale but it destroys the blessing."'
Sunan Ibn Majah Book 12, Hadith 73
← Previous Hadith "There are three to whom Allah will not speak on the Day of Resurrection nor will He look at them or purify them, and theirs will be a painful torment." I said: "Who are they, O Messenger of Allah? For they are indeed losers." He said: "The one who lets his garment hang beneath his ankles, the one who reminds another of what he has given him, and the one who sells his product by means of false oaths."

Sunan Ibn Majah Book 12, Hadith 72 Next Hadith → "Whoever buys a palm tree that has been pollinated, its fruits belong to the seller, unless the purchaser stipulated a condition." (Sahih)

Another chain from Ibn 'Umar, from the Prophet (ﷺ), with similar wording.

Sunan Ibn Majah Book 12, Hadith 74