BṚHADĀRAṆYAKA UPANISHAD · 5.7.1

विद्युद् ब्रह्मेत्य् आहुः ।
विदानाद् विद्युत् ।
विद्यत्य् एनं पाप्मनो य एवं वेद विद्युद् ब्रह्मेति ।
विद्युद् ध्य् एव ब्रह्म ॥

vidyud brahmety āhuḥ ।
vidānād vidyut ।
vidyaty enaṃ pāpmano ya evaṃ veda vidyud brahmeti ।
vidyud dhy eva brahma ॥

They say that lightning is Brahman, because lightning (vidyut) is called so from cutting off (vidânât). Whosoever knows this, that lightning is Brahman, him (that Brahman) cuts off from evil, for lightning indeed is Brahman.