Who planted this palm-a Muslim or an unbelievers The rest of the hadith is the same.
Sahih Muslim Book 22, Hadith 13
← Previous Hadith Anas reported Allah's Messenger (ﷺ) as saying Never does a Muslim plant trees or cultivate land and birds or a man or a beast eat out of them but that is a charity on his behalf.

Sahih Muslim Book 22, Hadith 12 Next Hadith → If You sell fruits to your brother (and Jabir b. Ahduthh reported through another chain of narrators: If you were to sell fruits to your brother) and these is a stricken with Calamity, it is not permissible for you to get anything from him. Why do you get the wealth of your brother, without jutification?

Sahih Muslim Book 22, Hadith 14