Great Sky Beyond Effort Tantra says:

Due to inborn unawareness, heart essence itself

Though ever here, goes unrecognized.

Through beginningless delusion

Samsara is engaged, wherein

Attracted to external objects and

With wrongful imputation

We wander the six realms of rebirth

Incurring various dissatisfactions,

Since grasping at objects is deeply ingrained.

The Root Sutra of Primordially Existent Phenomena (Ye srid bon gyi mdo rdza) says:

Though in no way different in terms of the base

Adventitious unawareness and primordial wisdom

Appear as any exalted qualities or degraded delusion; still

They move not one single iota from the base.

Though the base is utterly without delusion

Mental delusion modifies the base, and so

Not seeing the very base due to causes and conditions,

That very base appears as the bon-phenomena of samsara

Collection of Jewels Sutra (‘Dus pa rin po che’i mdo) :