The Book of Transactions
حَدَّثَنَا يَحْيَى بْنُ يَحْيَى، قَالَ قَرَأْتُ عَلَى مَالِكٍ عَنْ نَافِعٍ، عَنِ ابْنِ عُمَرَ، عَنْ زَيْدِ، بْنِ ثَابِتٍ أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم رَخَّصَ لِصَاحِبِ الْعَرِيَّةِ أَنْ يَبِيعَهَا بِخَرْصِهَا مِنَ التَّمْرِ .Zaid b. Thabit (Allah be pleased with him) reported Allah's Messenger (may peace he upon him) having given concession in case of 'ariyya for selling dry dates (with) fresh dates after measuring them out
From Sahih Muslim, whose reports the scholars accept as authentic.