Śatapatha Brāhmaṇa ("of a hundred paths") 9.3.3.11

9.3.3.11

yadvevāha | iyaṃ te rāṇmitrāya yantāsi yamana ūrje tvā vṛṣṭyai tvā prajānāṃ tvādhipatyāyetīdaṃ te rājyamabhiṣikto 'sītyetanmitrasya tvaṃ yantāsi yamana ūrje ca no 'si vṛṣṭyai ca no 'si prajānāṃ ca na ādhipatyāyāsītyupabruvata evainametadetasmai naḥ sarvasmā asyetasmai tvā sarvasmā abhyaṣicāmahīti tasmādu hedam mānuṣaṃ rājānamabhiṣiktamupabruvate

And when he says, 'This is thy realm; a supporter and sustainer art thou for the friend: for sustenance, for rain, for the lordship of creatures--thee!' this is to say, 'This is thy kingdom; thou art consecrated (anointed)! thou art thy friend's supporter and sustainer: for our sustenance art thou, for rain unto us art thou, for our lordship of creatures art thou!' They thereby entreat him, 'For all this art thou unto us: for all this have we consecrated thee!' And therefore people thus entreat a human king who has been consecrated.