"Any man who sells to two men, it is for the one who was first."[1]  

عَنِ النَّبِيِّ ﷺ قَالَ أَيُّمَا رَجُلٍ بَاعَ بَيْعًا مِنْ رَجُلَيْنِ فَهُوَ لِلأَوَّلِ مِنْهُمَا  

"If two (separate) authorized persons make a sale (of the same thing), then the first transaction is the one that is valid. "  

قَالَ رَسُولُ اللَّهِ ﷺ إِذَا بَاعَ الْمُجِيزَانِ فَهُوَ لِلأَوَّلِ