You'll never find any disagreement with the śāstra, sādhu and guru. Therefore Narottama dāsa Ṭhākura says, sādhu-śāstra-guru-vākya. That is our guidance. Sādhu. If you say Caitanya Mahāprabhu was a sādhu or a devotee, so His words and the words of the scriptures are the same. The sādhu will speak only on the authorities of śāstra. And śāstra means the description given by the sādhu. They are correlative. And guru means who follows the sādhu and the śāstra.
So these are very instructive. Sādhu who is always engaged in the service of the Lord, he is sādhu, bhakta. And śāstra. Śāstra means description of the activities of the sādhu and Bhagavān. Just like Śrīmad-Bhāgavatam. We are reading the story of Ajāmila. He became a sādhu, therefore his description of his life is inserted here. Prahlāda Mahārāja a sādhu; Dhruva Mahārāja, a sādhu; Ambarīṣa Mahārāja, a sādhu.
Formerly the kings were all sādhus, rājarṣi. Just like in the Bhagavad-gītā you have heard, imaṁ rājarṣayo viduḥ (BG 4.2). Formerly the kings were so exalted and they were so nice that they were, although they were sitting on the throne, they were dealing in politics, still, they were sādhu, just like ṛṣi. There are many instances.