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] (DE)
English reference (DE): Vol. 3, Book 12, Hadith 2190 (DE)
Arabic reference (DE): Book 12, Hadith 2274 (DE)