Shiva Purana
तस्मान्मन्त्रान्तरांस्त्यक्त्वा पञ्चाक्षरपरो भव ॥ तस्मिञ्जिह्वांतरगते न किंचिदिह दुर्लभम् ॥ ४६ ॥
Hence eschew all the other Mantras and devote yourself to this five-syllabled mantra. When that is in the mouth nothing is inaccessible here.
english translation
tasmAnmantrAntarAMstyaktvA paJcAkSaraparo bhava ॥ tasmiJjihvAMtaragate na kiMcidiha durlabham ॥ 46 ॥
hk transliteration by Sanscript