Shiva resides in the hearts of all beings.

sūkṣmātisūkṣmaṃ kalilasya madhye
viśvasya sraṣṭāram aneka-rūpam
viśvasyaikaṃ pariveṣṭitāraṃ
jñātvā śivaṃ śāntim atyantam eti ( SV Up IV-14 )

Finer beyond fineness. He hath hidden him in the midmost of this hustling chaos. He hath created this universe by taking many figures and as the One He encompasseth it around and girdeth it; having known Shiva, the Blessed One, man goeth to unutterable peace

The above verse explicitly identifies Lord Rudra with Shiva. The words " jñātvā śivaṃ " clearly says that the absolute is to be known or realised as SHIVA.,then only one can have supreme peace.

ghṛtāt paraṃ maṇḍam ivātisūkṣmaṃ
jñātvā śivaṃ sarva-bhūteṣu gūḍham
viśvasyaikaṃ pariveṣṭitāraṃ
jñātvā devaṃ mucyate sarva-pāśaiḥ ( SV Up IV-16)

As the rare and fine cream in clarified butter, and it is richer than the butter, so Shiva the Blessed One hath hidden Him in every one of all His creatures; but as the One He encompasseth this whole world and girdeth it around. Know God and thou breakest every bondage.

Here again Rishi Śvetāśvatara telling us to realise that, it is Shiva who resides in the hearts of all beings. (jñātvā śivaṃ sarva-bhūteṣu gūḍham ).

Om Namah Shivay.