Vidhi means Brahmā, the first created living being. He is the original student as well as professor of the Vedas. He learned it from Śrī Kṛṣṇa and taught Nārada first. So Nārada is the second ācārya in the line of spiritual disciplic succession. He is the representative of Brahmā, and therefore he is respected exactly like Brahmā, the father of all vidhis (regulations); similarly all other successive disciples in the chain are also equally respected as representatives of the original spiritual master.
Thus end the Bhaktivedanta purports of the First Canto, Fourth Chapter, of the Śrīmad-Bhāgavatam, entitled "The Appearance of Śrī Nārada."