Sahih al-Bukhari Book 34, Hadith 89
I saw the people buy foodstuff randomly (i.e. blindly without measuring it) in the lifetime of Allah's
Apostle and they were punished (by beating), if they tried to sell it before carrying it to their own
houses.
The Prophet (ﷺ) said, "The buyer of foodstuff should not sell it before it has been measured for him." Isma`il narrated instead, "He should not sell it before receiving it."
Rarely did the Prophet (ﷺ) fail to visit Abu Bakr's house everyday, either in the morning or in the evening. When the permission for migration to Medina was granted, all of a sudden the Prophet (ﷺ) came to us at noon and Abu Bakr was informed, who said, "Certainly the Prophet (ﷺ) has come for some urgent matter." The Prophet (ﷺ) said to Abu Bark, when the latter entered "Let nobody stay in your home." Abu Bakr said, "O Allah's Messenger (ﷺ)! There are only my two daughters (namely `Aisha and Asma') present." The Prophet (ﷺ) said, "I feel (am informed) that I have been granted the permission for migration." Abu Bakr said, "I will accompany you, O Allah's Messenger (ﷺ)!" The Prophet (ﷺ) said, "You will accompany me." Abu Bakr then said "O Allah's Messenger (ﷺ)! I have two she-camels I have prepared specially for migration, so I offer you one of them. The Prophet (ﷺ) said, "I have accepted it on the condition that I will pay its price."