Shiva Purana
एवं विलाप्य गायत्रीं प्रणवे शिववाचके ॥ अहं वृक्षस्य रेरिवेत्यनुवाकं जपेत्पुनः ॥ ६५ ॥
After dissolving Gāyatrī in the Praṇava identical with Śiva he shall recite the hymn “ahaṃ vṛkṣasya reriva.”
english translation
evaM vilApya gAyatrIM praNave zivavAcake ॥ ahaM vRkSasya rerivetyanuvAkaM japetpunaH ॥ 65 ॥
hk transliteration by Sanscript