Patanjali is talking about Omniscience of Ishvara and His significance in attaining the Yoga.
Verse 26
स एष पूर्वेषामपिगुरुः कालेनानवच्छेदात् ॥२६॥
sa eṣa pūrveṣām-api-guruḥ kālena-anavacchedāt ॥26॥
That (Isavara) is the Teacher of even the ancient teachers, since He is not limited by time.
In these verses, Sage Patanjali is talking about Omniscience of Ishvara and His significance in attaining the Yoga.
In verse 26, Ishvara is called as the Adi-Guru, the Adi-Yogi. It is true that all knowledge is within ourselves, but this has to be called forth by another knowledge. Although the capacity
to know is inside us, it must be called out, and that calling out of knowledge can only be got, a Yogi maintains, through another knowledge. Dead, insentient matter, never calls out
knowledge. It is the action of knowledge that brings out knowledge. Knowing beings must be with us to call forth what is in us, so these teachers were always necessary. The world was never without them, and no knowledge can come without them. God is the Teacher of all teachers, because these teachers, however great they may have been—gods or angels—were all bound and limited by time, and God is not limited by time. These are the two peculiar distinctions of the Yogis. The first is that in thinking of the limited, the mind must think of the unlimited, and that if one part of the perception is true the other must be, for the reason that their value as perceptions of the mind is equal. The very fact that man has a little knowledge, shows that God has unlimited knowledge. If I am to take one, why not the other? Reason forces me to take both or reject both. If I believe that there is a man with a little knowledge, I must also admit that there is someone behind him with unlimited knowledge. The second deduction is that no knowledge can come without a teacher. It is true as the modern philosophers say, that there is something in man which evolves out of him; all knowledge is in man, but certain environments are necessary to call it out. We cannot find any knowledge without teacher, if there are men teachers, god teachers, or angel teachers, they are all limited; who was the teacher before them? We are forced to admit, as a last conclusion, One Teacher, Who is not limited by time, and that One Teacher or infinite knowledge, without beginning or end, is called God.
PATANJALI YOGA SUTRAS