Mokṣa-Sannyāsa Yoga · Verse 37
यत्तदग्रे विषमिव परिणामेऽमृतोपमम् | तत्सुखं सात्त्विकं प्रोक्तमात्मबुद्धिप्रसादजम्
yat tad agre viṣam iva pariṇāme 'mṛtopamam | tat sukhaṃ sāttvikaṃ proktam ātma-buddhi-prasāda-jam
That which at first is like poison, but in the result like nectar — that pleasure is said to be sāttvic, born of the serenity of the mind of the Self.
Sāttvic pleasure: agre viṣam iva — at first like poison (difficult, austerity, effort). Pariṇāme amṛta-upamam — in the result, like nectar.
Ātma-buddhi-prasāda-jam — born of the serenity (prasāda) of the mind (buddhi) of the Self. It is the pleasure of yoga, of self-knowledge, which requires initial discipline but liberates in the end.