The words sādhur eva, "he is saintly," are very emphatic. They are a warning to the nondevotees that because of an accidental falldown a devotee should not be derided; he should still be considered saintly even if he has accidentally fallen down. And the word mantavyaḥ is still more emphatic. If one does not follow this rule, and derides a devotee for his accidental falldown, then one is disobeying the order of the Supreme Lord. The only qualification of a devotee is to be unflinchingly and exclusively engaged in devotional service.
In the Nṛsiṁha Purāṇa the following statement is given:
bhagavati ca harāv ananya-cetā
bhṛśa-malino 'pi virājate manuṣyaḥ
na hi śaśa-kaluṣa-cchabiḥ kadācit
timira-parābhavatām upaiti candraḥ
The meaning is that even if one fully engaged in the devotional service of the Lord is sometimes found engaged in abominable activities, these activities should be considered to be like the spots that resemble the mark of a rabbit on the moon. Such spots do not become an impediment to the diffusion of moonlight. Similarly, the accidental falldown of a devotee from the path of saintly character does not make him abominable.
(Bhagavad-Gita----9:30----purport).

In the material world the living beings are influenced by the three material modes of nature, namely goodness, passion and ignorance. But Śrī Nārada Muni is transcendental to all these material modes, and thus he can travel everywhere unrestricted. He is a liberated spaceman. The causeless mercy of Lord Viṣṇu is unparalleled, and such mercy is perceived by the devotees only by the grace of the Lord. Therefore, the devotees never fall down, but the materialists, i.e., the fruitive workers and the speculative philosophers, do fall down, being forced by their respective modes of nature. The ṛṣis, as above mentioned, cannot enter into the transcendental world like Nārada. This fact is disclosed in the Narasiṁha Purāṇa. Ṛṣis like Marīci are authorities in fruitive work, and ṛṣis like Sanaka and Sanātana are authorities in philosophical speculations. But Śrī Nārada Muni is the prime authority for transcendental devotional service of the Lord.
(Srimad Bhagavatam----1:6:31----purport).

The Lord can be worshiped in all stages of life. For instance, even in the wombs of their mothers Mahārāja Prahlāda and Mahārāja Parīkṣit worshiped the Lord; even in his very childhood, at the age of only five years, Dhruva Mahārāja worshiped the Lord; even in full youth, Mahārāja Ambarīṣa worshiped the Lord; and even at the last stage of his frustration and old age Mahārāja Dhṛtarāṣṭra worshiped the Lord. Ajāmila worshiped the Lord even at the point of death, and Citraketu worshiped the Lord even in heaven and in hell. In theNarasiṁha Purāṇa it is said that as the hellish inhabitants began to chant the holy name of the Lord they began to be elevated from hell towards heaven. Durvāsā Muni has also supported this view: mucyeta yan-nāmny udite nārako 'pi. "Simply by chanting the holy name of the Lord the inhabitants of hell became released from their hellish persecution."
(Srimad Bhagavatam----2:9:36----purport).

‘Even a mleccha who is being killed by the tusk of a boar and who cries in distress again and again, "hā rāma, hā rāma" attains liberation. What then to speak of those who chant the holy name with veneration and faith?'
This refers to an instance in which a meat-eater being killed by a boar uttered the words hā rāma, hā rāma again and again at the time of his death. Since this is a quotation from theNṛsiṁha Purāṇa, this indicates that in the purāṇic age there must also have been mlecchas and yavanas (meat-eaters), and the words hā rāma, meaning "condemned," were also uttered in those days. Thus Haridāsa Ṭhākura gives evidence that even a meat-eater who condemns something by uttering the words hā rāma gets the benefit of chanting the holy name that the devotee chants to mean "O my Lord Rāma!"
(Sri caitanya Caritamrta----3:3:56----translation and purport).

Those who are less intelligent want to worship different demigods for some material gain rather than worship Kṛṣṇa. But here it is stated that a devotee who is always engaged in offering prayers to the Lord is worshipable even by the demigods themselves. The pure devotees have nothing to ask from any demigod; rather, the demigods are anxious to offer prayers to the pure devotees.
In the Nṛsiṁha Purāṇa it is stated, "Any person who comes before the Deity of Lord Kṛṣṇa and begins to chant different prayers is immediately relieved from all the reactions of sinful activities and becomes eligible, without any doubt, to enter into the Vaikuṇṭhaloka."
(Nectar of Devotion).

To meditate means to engage the mind in thinking of the form of the Lord, the qualities of the Lord, the activities of the Lord and the service of the Lord. Meditation does not mean anything impersonal or void. According to Vedic literature, meditation is always on the form of Viṣṇu.
In the Nṛsiṁha Purāṇa there is a statement about meditation on the form of the Lord. It is said there, "Meditation focusing on the lotus feet of the Supreme Personality of Godhead has been accepted as transcendental and beyond the experience of material pain and pleasure. By such meditation, even one who is grossly miscreant can be delivered from the sinful reactions of his life."
(Nectar of Devotion).

In the Hari-bhakti-vilāsa there is the following statement about self-surrender: "My dear Lord, a person who has surrendered himself unto You, who is in firm conviction that he is Yours, and who actually acts in that way by his body, mind and words, can actually relish transcendental bliss."
In the Nṛsiṁha Purāṇa, Lord Nṛsiṁhadeva says, "Anyone who prays unto Me and takes shelter from Me becomes My ward, and I protect him always from all sorts of calamities."
(Nectar of Devotion).

In the Nṛsiṁha Purāṇa it is stated, "If a person has completely engaged his mind, body and activities in the service of the Supreme Godhead, but externally he is found to be engaged in some abominable activities, these abominable activities will surely be very quickly vanquished by the influence of his staunch devotional force." The example is given that on the full moon there are some spots which may appear to be pockmarks. Still, the illumination spread by the full moon cannot be checked. Similarly, a little fault in the midst of volumes of devotional service is not at all to be counted as a fault. Attachment for Kṛṣṇa is transcendental bliss. Amid unlimited volumes of transcendental bliss, a spot of some material defect cannot act in any way.
(Nectar of Devotion).

In the Nṛsiṁha Purāṇa there is a statement about King Ikṣvāku which illustrates this state of ecstatic love. Because of his great affection for Kṛṣṇa, King Ikṣvāku became greatly attached to the black cloud, the black deer, the deer's black eyes and the lotus flower, which is always compared to the eyes of the Lord. In the Tenth Canto, Thirty-eighth Chapter, verse 10, of the Bhāgavatam, Akrūra thinks, "Since the Lord has now appeared to diminish the great burden of the world and is now visible to everyone's eyes in His personal transcendental body, when we see Him before us, is that not the ultimate perfection of our eyes?" In other words, Akrūra realized that the perfection of the eyes is fulfilled when one is able to see Lord Kṛṣṇa. Therefore, when Lord Kṛṣṇa was visible on the earth by direct appearance, everyone who saw Him surely attained perfection of sight.

(Nectar of Devotion).