Shiva Purana
असाधितस्साधितो वा सिध्यत्वेन न संशयः ॥ श्रद्धातिशययुक्तस्य मयि मंत्रे तथा गुरौ ॥ ७० ॥
If one has faith in me, the mantra and the preceptor, the mantra will undoubtedly be achieved whether it is Asādhita or Sādhita.
english translation
asAdhitassAdhito vA sidhyatvena na saMzayaH ॥ zraddhAtizayayuktasya mayi maMtre tathA gurau ॥ 70 ॥
hk transliteration by Sanscript