Yōga Sūtra 1.26

पूर्वेषामपि गुरुः कालेनानवच्छेदात्।

pūrvēṣāmapi guruḥ kālēnānavacchēdāt।

[पूर्वेषाम् अपि गुरुः कालेन अनवच्छेदात्।
pūrvēṣām = to the ancients; api = as well; guruḥ = teacher; kālēna = by time; anavacchēdāt = from the absence of division or separation;]

HE is the teacher to ancients as well, as he is not seperated by the divisions of time.

On more attribute of īśvaraḥ, He is beyond time. Hence, he is the teacher to all previous beings as well.