Skandapurana 1.4.38.163

1.4.38.163

"maṃtrā daivatā yadyadvidvānmantravatkaroti devatābhireva tatkaroti yaddadāni devatābhireva taddadāti yatpratigṛhṇāti devatābhireva tatpratigṛhṇāti tasmānnāmantravatpratigṛhṇīyāt nāmantravatpratipadyate" iti.. 40.163 ..

“The mantras are the deities. Whatever the learned person performs with a mantra, he performs with the deities themselves; whatever he gives, he gives through the deities themselves; whatever he receives, he receives through the deities themselves. Therefore one should not receive without a mantra, nor does one offer without a mantra.” 40.163