should we fast on Dvadasi

[Paramananda das]

should we fast on Dvadasi ?
EKADASIM UPAVASED DVADASIM ATHAVA PUNAH
VIMISRAM VAPI KURVITA NA DASAMYA YUTAM KVACIT
(HARI BHAKTI VILASA 12/202 from SAURA DHARMOTTARA)
Ekadasi and Dvadasi are both qualified for fasting. Furthermore, one should fast when Ekadasi is combined with Dvadasi, but one should never fast when Ekadasi is combined with Dasami.
one nice devotee told me he sometimes fast on Dasami also ,,,it is very inauspicious ,,we should only fast on Ekadasi ,,,I never read that we should fast on Dvadasi also ,though some Ekadasis mention and recommend restriction on things to be taken on Dasami and Dvadasi,, the rule is to fast on Ekadasi not mixed with Dasami ,,so if someone wants to brake the fast on Dvadasi and continue to fast who can stop such a person,But from what I read Ambarish Maharaja did not fast on Dvadasi and he is a Mahajana and an example of a devotee that did full Atma nivedana full surrender to Krsna in all the 9 aspects of devotional service .
Srila Prabhupada mentioned our main focus is to chant Hare Krsna
.He is not in the list of the 12 Mahajanas but is an authority in full surrender as confirmed in Srimad Bhagavatam
svayambhūr nāradaḥ śambhuḥ
kumāraḥ kapilo manuḥ
prahlādo janako bhīṣmo
balir vaiyāsakir vayam
Śrīmad-Bhāgavatam 6.3.20
Śrī Dharmarāja said, “Lord Brahmā, Bhagavān Nārada, Lord Śiva, the four kumāras, Lord Kapila the son of Devahūti, Svāyambhuva Manu, Prahlāda Mahārāja, Janaka Mahārāja, Grandfather Bhīṣma, Bali Mahārāja, Śukadeva Gosvāmī, and I myself know the real religious principles.”
"In the Hari-bhakti-vilasa 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 Nrsimha Purana, Lord Nrsimhadeva 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, Chapter 11
“Maharaja Pariksit attained the highest perfection, shelter at Lord Krishna’s lotus feet, simply by hearing about Lord Vishnu. Sukadeva Goswami attained perfection simply by reciting Srimad-Bhagavatam. Prahlada Maharaja attained perfection by remembering the Lord. The goddess of fortune attained perfection by massaging the transcendental legs of Maha Vishnu. Maharaja Prthu attained perfection by worshipping the deity, and Akrura attained perfection by offering prayers unto the Lord. Vajrangaji [Hanuman] attained perfection by rendering service to Lord Ramacandra, and Arjuna attained perfection simply by being Krishna’s friend. Bali Maharaja attained perfection by dedicating everything to the lotus feet of Krishna.” (BRS 1.2.265). It is further explained that Ambarish Maharaja engaged in all nine processes, fully engaging his mind, senses and entire being in the Lord’s service.
Srila Prabhupada has described Ambarish Maharaja in Bhagavad Gita:
BG 2.61, Translation and Purport: One who restrains his senses, keeping them under full control, and fixes his consciousness upon Me, is known as a man of steady intelligence.
That the highest conception of yoga perfection is Kṛṣṇa consciousness is clearly explained in this verse. And unless one is Kṛṣṇa conscious it is not at all possible to control the senses. As cited above, the great sage Durvāsā Muni picked a quarrel with Mahārāja Ambarīṣa, and Durvāsā Muni unnecessarily became angry out of pride and therefore could not check his senses. On the other hand, the king, although not as powerful a yogī as the sage, but a devotee of the Lord, silently tolerated all the sage's injustices and thereby emerged victorious. The king was able to control his senses because of the following qualifications, as mentioned in the Śrīmad-Bhāgavatam (9.4.18-20):
sa vai manaḥ kṛṣṇa-padāravindayor
vacāṁsi vaikuṇṭha-guṇānuvarṇane
karau harer mandira-mārjanādiṣu
śrutiṁ cakārācyuta-sat-kathodaye
mukunda-liṅgālaya-darśane dṛśau
tad-bhṛtya-gātra-sparśe 'ṅga-saṅgamam
ghrāṇaṁ ca tat-pāda-saroja-saurabhe
śrīmat-tulasyā rasanāṁ tad-arpite
pādau hareḥ kṣetra-padānusarpaṇe
śiro hṛṣīkeśa-padābhivandane
kāmaṁ ca dāsye na tu kāma-kāmyayā
yathottama-śloka-janāśrayā ratiḥ
"King Ambarīṣa fixed his mind on the lotus feet of Lord Kṛṣṇa, engaged his words in describing the abode of the Lord, his hands in cleansing the temple of the Lord, his ears in hearing the pastimes of the Lord, his eyes in seeing the form of the Lord, his body in touching the body of the devotee, his nostrils in smelling the flavor of the flowers offered to the lotus feet of the Lord, his tongue in tasting the tulasī leaves offered to Him, his legs in traveling to the holy place where His temple is situated, his head in offering obeisances unto the Lord, and his desires in fulfilling the desires of the Lord... and all these qualifications made him fit to become a mat-para devotee of the Lord."
The word mat-para is most significant in this connection. How one can become mat-para is described in the life of Mahārāja Ambarīṣa. Śrīla Baladeva Vidyābhūṣaṇa, a great scholar and ācārya in the line of the mat-para, remarks, mad-bhakti-prabhāvena sarvendriya-vijaya-pūrvikā svātma-dṛṣṭiḥ sulabheti bhāvaḥ. "The senses can be completely controlled only by the strength of devotional service to Kṛṣṇa." Also, the example of fire is sometimes given: "As a blazing fire burns everything within a room, Lord Viṣṇu, situated in the heart of the yogī, burns up all kinds of impurities." The Yoga-sūtra also prescribes meditation on Viṣṇu, and not meditation on the void. The so-called yogīs who meditate on something other than the Viṣṇu form simply waste their time in a vain search after some phantasmagoria.
We have to be Kṛṣṇa conscious—devoted to the Personality of Godhead. This is the aim of the real yoga.