Shiva Purana

siva.sh/siva-purana/vishweshwara-samhita/17/149

उत्तरोत्तर वै शिष्ट्यात्पूजायामुत्तरोत्तरम् । फलं वैशिष्ट्यरूपं च दुर्विज्ञेयं मनीषिभिः १४९ ।

sanskrit

With progressive excellence in worship, the fruits (rewards) of the worship become progressively greater, in the form of special qualities that are difficult to comprehend even by the most wise philosophers.

english translation

uttarottara vai ziSTyAtpUjAyAmuttarottaram | phalaM vaiziSTyarUpaM ca durvijJeyaM manISibhiH 149 |

hk transliteration by Sanscript