It was narrated from Ibn 'Umar that the Messenger of Allah ﷺ said:
"Whoever buys a palm tree that has been pollinated, its fruits belong to the seller, unless the purchaser stipulated a condition."
Another chain from Ibn 'Umar, from the Prophet ﷺ, with similar wording.

حَدَّثَنَا هِشَامُ بْنُ عَمَّارٍ، حَدَّثَنَا مَالِكُ بْنُ أَنَسٍ، قَالَ حَدَّثَنِي نَافِعٌ، عَنِ ابْنِ عُمَرَ، أَنَّ النَّبِيَّ ـ ﷺ ـ قَالَ " مَنِ اشْتَرَى نَخْلاً قَدْ أُبِّرَتْ فَثَمَرَتُهَا لِلْبَائِعِ إِلاَّ أَنْ يَشْتَرِطَ الْمُبْتَاعُ " .