Skandapurana 6.3.133.27

6.3.133.27

rājā vṛkṣo brāhmaṇāstasya mūlaṃ bhṛtyāḥ parṇā mantriṇastasya śākhāḥ .
tasmānmūlaṃ yatnato rakṣaṇīyaṃ mūle gupte nāsti vṛkṣasya nāśaḥ .. 27 ..

A king is a tree; the brahmins are its roots; servants are the leaves, and ministers are its branches. / Therefore, the root must be protected with effort; when the root is protected, there is no destruction of the tree.