Sādhu, they are very titikṣavaḥ, ārjavam. Similarly, brāhmaṇa qualification is also . . . satyaṁ śaucaṁ samo damas titikṣā. Titikṣā, tolerant; ārjava, simplicity; jñānaṁ vijñānam āstikyaṁ brahma-karma svabhāva-jam (BG 18.42). So similarly, sādhu. There must be a class of men in the society first-class sādhu. Then the society will improve. If everyone is debauch and śūdra, then how the society will be peaceful? There is . . . therefore, to organize the society, Kṛṣṇa recommends, cātur-varṇyaṁ mayā sṛṣṭaṁ guṇa-karma-vibhāgaśaḥ (BG 4.13). There must be ideal brāhmaṇa. There must be ideal kṣatriya, ideal vaiśya. And balance, all śūdras. But nobody's caring that.
So sādhu means devotee, Kṛṣṇa's devotee. That is called sādhu. Here it is stated, sa eva sādhuṣu kṛtaḥ. The same association, sādhu-saṅga. (CC Madhya 22.83). So who is sādhu? Sādhu means devotee. It is defined by Kṛṣṇa Himself: sādhur eva sa mantavyaḥ. He's sādhu. Who? Bhajate mām ananya-bhāk. Api cet su-durācāro bhajate mām ananya-bhāk, sādhur eva sa mantavyaḥ (BG 9.30). He's sādhu. Anyone who is, without any reservation, has begun serving Kṛṣṇa and engaged in Kṛṣṇa consciousness—that is the definition of sādhu. Titikṣava.