"The Messenger of Allah said: 'No man is bound by a transaction involving the sale of something that he does not possess.'''  

قَالَ رَسُولُ اللَّهِ ﷺ لَيْسَ عَلَى رَجُلٍ بَيْعٌ فِيمَا لاَ يَمْلِكُ  

Yahya related to me from Malik from Ibn Shihab from Irak ibn Malik and Sulayman ibn Yasar that a man of the Banu Sad ibn Layth was running a horse and it trod on the finger of a man from the Juhayna tribe. It bled profusely, and he died. Umar ibn al-Khattab said to those against whom the claim was made. "Do you swear by Allah with fifty oaths that he did not die of it?" They refused and stopped themselves from doing it. He said to the others, "Will you take an oath?" They refused, so Umar ibn al-Khattab gave a judgement that the Banu Sad had to pay half the full blood-money. Malik said, "One does not act on this."  

أَنَّ رَجُلاً مِنْ بَنِي سَعْدِ بْنِ لَيْثٍ أَجْرَى فَرَسًا فَوَطِئَ عَلَى إِصْبَعِ رَجُلٍ مِنْ جُهَيْنَةَ فَنُزِيَ مِنْهَا فَمَاتَ فَقَالَ عُمَرُ بْنُ الْخَطَّابِ لِلَّذِي ادُّعِيَ عَلَيْهِمْ أَتَحْلِفُونَ بِاللَّهِ خَمْسِينَ يَمِينًا مَا مَاتَ مِنْهَا فَأَبَوْا وَتَحَرَّجُوا وَقَالَ لِلآخَرِينَ أَتَحْلِفُونَ أَنْتُمْ فَأَبَوْا فَقَضَى عُمَرُ بْنُ الْخَطَّابِ بِشَطْرِ الدِّيَةِ عَلَى السَّعْدِيِّينَ قَالَ مَالِكٌ وَلَيْسَ الْعَمَلُ عَلَى هَذَا  

"The Messenger of Allah said: 'No man is bound by a transaction involving the sale of something that he does not possess.''' (Using translation from Nasāʾī 4612)  

قَالَ رَسُولُ اللهِ ﷺ «لَيْسَ عَلَى الرَّجُلِ بَيْعٌ فِيمَا لَا يَمْلِكُ»