Shiva Purana
उपांशूच्चारयोगेन जुहुयादाहुतित्रयम् ॥ पुनस्संपूज्य देवेशं मन्त्रवैकल्यशुद्धये ॥ ४३ ॥
In order to expiate for the shortcomings in the Mantra he shall worship the lord of the gods and pour three Āhutis by muttering the mantra.
english translation
upAMzUccArayogena juhuyAdAhutitrayam ॥ punassaMpUjya devezaM mantravaikalyazuddhaye ॥ 43 ॥
hk transliteration by Sanscript