Tinyana 41 · תנינא מ״א

Occasionally, God works miracles through the master decisors of Halakhah, as in “His miracles and His pronouncement of judgments” (1 Chronicles 16:12). “His pronouncement of judgments”—his issuing a ruling that it should be so—brings about a miracle.

Having been recognized as an adjudicator, his opinion is accepted when he issues a ruling in matters of prohibited-and-permitted and the like. It is the same when he issues a decision on any matter. His opinion is accepted and miracles are performed through him.

This relates to the miracles which people tell about the leading sages of previous generations.