As the moon reflected on water appears to the seer to tremble due to being associated with the quality of the water, so the self associated with matter appears to be qualified as matter.
Srimad Bhagavata Purana
श्रीमद्भागवतमहापुराणम्
मूल श्लोकः
यथा जले चन्द्रमसः कम्पादिस्तत्कृतो गुणः । दृश्यतेऽसन्नपि द्रष्टुरात्मनोऽनात्मनो गुणः
yathā jale candramasaḥ kampādistatkṛto guṇaḥ | dṛśyate'sannapi draṣṭurātmano'nātmano guṇaḥ
SB 3.7.11