SB 10.87.45

Śukadeva Gosvāmī said: When Śrī Nārāyaṇa Ṛṣi ordered him in this way, the self-possessed sage Nārada, whose vow is as heroic as a warrior's, accepted the command with firm faith. Now successful in all his purposes, he thought about what he had heard, O King, and replied to the Lord as follows. KB 10.87.45 Śrī Nārada Muni is a naiṣṭhika-brahmacārī. There are four types of brahmacārīs. The first is called sāvitra, which refers to a brahmacārī who, after initiation and the sacred thread ceremony, must observe at least three days of celibacy. The next is called prājāpatya, which refers to a brahmacārī who strictly observes celibacy for at least one year after initiation. The next is called brāhma-brahmacārī, which refers to a brahmacārī who observes celibacy from the time of initiation up to the time of the completion of his study of the Vedic literature. The next stage is called naiṣṭhika, which refers to a brahmacārī who is celibate throughout his whole life. Out of these, the first three are upakurvāṇa, which means that the brahmacārī can marry later, after the brahmacārī period is over. The naiṣṭhika-brahmacārī, however, is completely reluctant to have any sex life; therefore the Kumāras and Nārada are known as naiṣṭhika-brahmacārīs. Such brahmacārīs are called vīra-vrata because their vow of celibacy is as heroic as the vows of the kṣatriyas. The brahmacārī system of life is especially advantageous in that it increases the power of memory and determination. It is specifically mentioned in this connection that because Nārada was a naiṣṭhika-brahmacārī he could remember whatever he heard from his spiritual master and would never forget it. One who can remember everything perpetually is called a śruti-dhara. A śruti-dhara brahmacārī can repeat verbatim all that he has heard, without notes and without reference to books. The great sage Nārada has this qualification, and therefore, having taken instructions from Nārāyaṇa Ṛṣi, he is engaged in propagating the philosophy of devotional service all over the world. Because such great sages can remember everything, they are thoughtful, self-realized and completely fixed in the service of the Lord. Thus the great sage Nārada, after hearing from his spiritual master Nārāyaṇa Ṛṣi, became completely realized. He became established in the truth, and he became so happy that he offered prayers to Nārāyaṇa Ṛṣi.