Sunan an-Nasa'i 4551

أَخْبَرَنَا عَلِيُّ بْنُ حُجْرٍ، قَالَ حَدَّثَنَا إِسْمَاعِيلُ، عَنْ أَيُّوبَ، عَنْ نَافِعٍ، عَنِ ابْنِ عُمَرَ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم نَهَى عَنْ بَيْعِ النَّخْلَةِ حَتَّى تَزْهُوَ وَعَنِ السُّنْبُلِ حَتَّى يَبْيَضَّ وَيَأْمَنَ الْعَاهَةَ نَهَى الْبَائِعَ وَالْمُشْتَرِيَ ‏.‏

It was narrated from Ibn 'umar that:the Messenger of Allah forbade selling dates in the trees before they ripen or selling ears of corn before the grains become visible and there is no fear of blight. He forbade that to the seller ad the buyer

Reference

Sunan an-Nasa'i 4551

In-book

Book 44, Hadith 103