Bhagavad Gita 9.2
राजविद्या राजगुह्यं पवित्रमिदमुत्तमम्। प्रत्यक्षावगमं धर्म्यं सुसुखं कर्तुमव्ययम्।।9.2।।
rājavidyā rājaguhyaṃ pavitramidamuttamam| pratyakṣāvagamaṃ dharmyaṃ susukhaṃ kartumavyayam||9.2||
rajavidya rajaguhyam pavitramidamuttamam pratyakshavagamam dharmyam susukham kartumavyayam9.2
Meaning
This is the king of all knowledge, the king of all secrets, supremely purifying, directly perceivable, righteous, easy to practice, and imperishable. It is the highest spiritual wisdom.
यह ज्ञान राजविद्या और राजगुह्य एवं पवित्र, उत्तम, प्रत्यक्ष ज्ञानवाला और धर्मयुक्त है, तथा करने में सरल और अव्यय है।
This is verse 2 of 34 in Chapter 9 (Raja Vidya Raja Guhya Yoga) of the Bhagavad Gita.