Sahih al-Bukhari Book 34, Hadith 35
The Prophet (ﷺ) aid, "The buyer and the seller have the option to cancel or to confirm the deal, as long as
they have not parted or till they part, and if they spoke the truth and told each other the defects of the
things, then blessings would be in their deal, and if they hid something and told lies, the blessing of
the deal would be lost."
An Ansari man, called Abu Shu'aib, came and told his butcher slave, "Prepare meals sufficient for five persons, for I want to invite the Prophet (ﷺ) along with four other persons as I saw signs of hunger on his face." Abu Shu'aib invited them and another person came along with them. The Prophet (ﷺ) said (to Abu Shu'aib), This man followed us, so if you allow him, he will join us, and if you want him to return, he will go back." Abu Shu'aib said, "No, I have allowed him (i.e. he, too, is welcomed to the meal).
The Prophet (ﷺ) said "Certainly a time will come when people will not bother to know from where they earned the money, by lawful means or unlawful means." (See Hadith no. 2050)