It was narrated from 'Uqbah bin 'Amir or Samurah bin Jundab that the Messenger of Allah (ﷺ) said:
"Any man who sells to two men, it is for the one who was first."[1] (ES)
English reference (ES): Vol. 3, Book 12, Hadith 2190 (ES)
Arabic reference (ES): Book 12, Hadith 2274 (ES)