Musannaf Ibn Abi Shayba 13:1226

Abu Bakr narrated to us, he said: 'Abdah bin Sulayman narrated to us, from Sa'id bin Abi 'Arubah, from Qatadah, from Sulayman bin Yasar, that Zayd bin Thabit and Al-Zubayr bin Al-'Awwam saw no harm in a man buying what is on the tops of the palm trees when it has ripened, then selling it on the tops of the palm trees before he harvests it.