Shiva Purana
गुरुश्च परिपूर्णोऽस्मि शिव इत्यचलस्थितिः॥ समाधिमाचरेत्सम्यङ्मुहूर्त्तं गूढमानसः ॥ ४२ ॥
I am the teacher and I am perfect, Shiva, and I am unchanging. One should practice samadhi for a proper moment with a concealed mind.
english translation
guruzca paripUrNo'smi ziva ityacalasthitiH॥ samAdhimAcaretsamyaGmuhUrttaM gUDhamAnasaH ॥ 42 ॥
hk transliteration by Sanscript