Musannaf Ibn Abi Shayba 30:1

Abu Bakr Abdullah ibn Abi Shaybah narrated to us, from Sufyan ibn Uyaynah, from Ibn Abi Najih, from Mujahid, who said: The ground of Paradise is of silver, and its soil is musk, and the roots of its trees are gold and silver, and its branches are pearls, chrysolite, and rubies. The leaves and the fruit are beneath that. Whoever eats while standing, it does not harm him; whoever eats while sitting, it does not harm him; and whoever eats while reclining, it does not harm him. "And its clusters of fruit will be lowered in low lowering."