Sunan an-Nasa'i 4614
It was narrated that 'Abdullah Ibn Abi Awfa about paying in advance. He said:
'We used to pay in advance during the time of the Messenger of Allah and Abu Bakr and 'Umar, for wheat, barley and dates, paying people whom we did not know if they had those things or not.'''Ibn Abza said meaning, similarly.
أَخْبَرَنَا عُبَيْدُ اللَّهِ بْنُ سَعِيدٍ، قَالَ حَدَّثَنَا يَحْيَى، عَنْ شُعْبَةَ، عَنْ عَبْدِ اللَّهِ بْنِ أَبِي الْمُجَالِدِ، قَالَ سَأَلْتُ ابْنَ أَبِي أَوْفَى عَنِ السَّلَفِ، قَالَ كُنَّا نُسْلِفُ عَلَى عَهْدِ رَسُولِ اللَّهِ صلى الله عليه وسلم وَأَبِي بَكْرٍ وَعُمَرَ فِي الْبُرِّ وَالشَّعِيرِ وَالتَّمْرِ إِلَى قَوْمٍ لاَ أَدْرِي أَعِنْدَهُمْ أَمْ لاَ ‏.‏ وَابْنُ أَبْزَى قَالَ مِثْلَ ذَلِكَ ‏.‏