Shiva Purana
अन्योन्यं तारयेन्नौका किं शिला तारयेच्छिलाम् ॥ एतस्या नाममात्रेण मुक्तिर्वै नाममात्रिका ॥ ३८ ॥
Two boats can carry each other across the river. A piece of rock cannot take another piece of rock across the river. If the preceptor is nominal, the liberation too is nominal.
english translation
anyonyaM tArayennaukA kiM zilA tArayecchilAm ॥ etasyA nAmamAtreNa muktirvai nAmamAtrikA ॥ 38 ॥
hk transliteration by Sanscript