Hakim asked (the Prophet): Messenger of Allah, a man comes to me and wants me to sell him something which is not in my possession. Should I buy it for him from the market? He replied: Do not sell what you do not possess.
يَا رَسُولَ اللَّهِ يَأْتِينِي الرَّجُلُ فَيُرِيدُ مِنِّي الْبَيْعَ لَيْسَ عِنْدِي أَفَأَبْتَاعُهُ لَهُ مِنَ السُّوقِ فَقَالَ لاَ تَبِعْ مَا لَيْسَ عِنْدَكَ