The Hari-bhakti-vilāsa cites the following quotation from Skanda Purāṇa concerning the blaspheming of a Vaiṣṇava:

yo hi bhāgavataṁ lokam
upahāsaṁ nṛpottama
karoti tasya naśyanti
artha-dharma-yaśaḥ-sutāḥ

nindāṁ kurvanti ye mūḍhā
vaiṣṇavānāṁ mahātmanām
patanti pitṛbhiḥ sārdhaṁ
mahā-raurava-saṁjñite

hanti nindati vai dveṣṭi
vaiṣṇavān nābhinandati
krudhyate yāti no harṣaṁ
darśane patanāni ṣaṭ

In this conversation between Mārkaṇḍeya and Bhagīratha, it is said: "My dear King, if one derides an exalted devotee, he loses the results of his pious activities, his opulence, his reputation and his sons. Vaiṣṇavas are all great souls. Whoever blasphemes them falls down to the hell known as Mahāraurava. He is also accompanied by his forefathers. Whoever kills or blasphemes a Vaiṣṇava and whoever is envious of a Vaiṣṇava or angry with him, or whoever does not offer him obeisances or feel joy upon seeing a Vaiṣṇava, certainly falls into a hellish condition."

The Hari-bhakti-vilāsa (10.314) also gives the following quotation from Dvārakā-māhātmya:

kara-patraiś ca phālyante
sutīvrair yama-śāsanaiḥ
nindāṁ kurvanti ye pāpā
vaiṣṇavānāṁ mahātmanām

In a conversation between Prahlāda Mahārāja and Bali Mahārāja, it is said, "Those sinful people who blaspheme Vaiṣṇavas, who are all great souls, are subjected very severely to the punishment offered by Yamarāja."

In the Bhakti-sandarbha (313) there is a statement concerning the blaspheming of Lord Viṣṇu.

ye nindanti hṛṣīkeśaṁ
tad-bhaktaṁ puṇya-rūpiṇam
śata-janmārjitaṁ puṇyaṁ
teṣāṁ naśyati niścitam

te pacyante mahā-ghore
kumbhīpāke bhayānake
bhakṣitāḥ kīṭa-saṅghena
yāvac candra-divākarau
śrī-viṣṇor avamānanād
gurutaraṁ śrī-vaiṣṇavollaṅghanam

tadīya-dūṣaka-janān
na paśyet puruṣādhamān
taiḥ sārdhaṁ vañcaka-janaiḥ
saha-vāsaṁ na kārayet

"One who criticizes Lord Viṣṇu and His devotees loses all the benefits accrued in a hundred pious births. Such a person rots in the Kumbhīpāka hell and is bitten by worms as long as the sun and moon exist. One should therefore not even see the face of a person who blasphemes Lord Viṣṇu and His devotees. Never try to associate with such persons."

In his Bhakti-sandarbha (265), Jīva Gosvāmī further quotes from Śrīmad-Bhāgavatam (10.74.40):

nindāṁ bhagavataḥ śṛṇvan
tat-parasya janasya vā
tato nāpaiti yaḥ so 'pi
yāty adhaḥ sukṛtāc cyutaḥ

"If one does not immediately leave upon hearing the Lord or the Lord's devotee blasphemed, he falls down from devotional service." Similarly, Lord Śiva's wife Satī states in Śrīmad-Bhāgavatam (4.4.17):

karṇau pidhāya nirayād yad akalpa īśe
dharmāvitary asṛṇibhir nṛbhir asyamāne
chindyāt prasahya ruśatīm asatīṁ prabhuś cej
jihvām asūn api tato visṛjet sa dharmaḥ

"If one hears an irresponsible person blaspheme the master and controller of religion, he should block his ears and go away if unable to punish him. But if one is able to kill, then one should by force cut out the blasphemer's tongue and kill the offender, and after that he should give up his own life."