Musnad Ahmad 613:1

Waki’ and ‘Abd al-Rahman narrated to us, from Sa’id ibn ‘Abd al-‘Aziz, from Sulayman ibn Musa, from Abu Sayyar—‘Abd al-Rahman said: al-Muta’i—he said: I said, "O Messenger of Allah, I have palm trees." He said, "Pay the tithe (zakat)." He said: I said, "O Messenger of Allah, protect them for me." He said: So he protected them for me. ‘Abd al-Rahman said: "Protect its mountain for me." He said: So he protected its mountain for me.