What does masood mean when he say "be careful you don't cut the heart of the palm?"

He means do not harm the palm tree: to cut around the dates,

I, however, had begun to think about Masood’s phrase, the heart of the palm. I pictured the palm tree as something with feeling, something possessed of a heart that throbbed. I remembered Masood’s remark to me when he had once seen me playing with the branch of a young palm tree: Palm trees, my boy, like humans, experience joy and suffering. And I had felt an inward and unreasoned embarrassment.