Garudapurana 2.1.11

2.1.11

na rajo na tamaścaiva sattvaṃ tābhyāṃ ca miśritam /
yatra pravartate naiva sattvameva pravartate //

[There is] neither rajas nor tamas, nor sattva mixed with the two; / where [sattva mixed with them] does not prevail at all, sattva alone prevails;