ततः सन्तप्तहृदयः स्मरन्निग्रहमात्मनः।
विनिःश्वस्य विनिःश्वस्य कृतवैरो महात्मना॥
स दक्षिणां दिशं गत्वा महिष्या सह राघव।
तताप परमं घोरं विश्वामित्रो महत्तपः॥
tataḥ santapta-hṛdayaḥ smaran nigraham ātmanaḥ
viniḥśvasya viniḥśvasya kṛta-vairo mahātmanā
sa dakṣiṇāṁ diśaṁ gatvā mahiṣyā saha rāghava
tatāpa paramaṁ ghoraṁ viśvāmitro mahat tapaḥ
tataḥ santapta-hṛdayaḥ = with a burning heart; smaran = remembering; nigraham = humiliation; ātmanaḥ = his; viniḥśvasya viniḥśvasya = sighed repeatedly; kṛta-vairaḥ = and having become an enemy; mahā-ātmanā = of the great soul Vasiṣṭha; saḥ dakṣiṇām diśam gatvā = departed to the south; mahiṣyā saha = with his queen; rāghava = O Rāghava; tatāpa = and performed; paramam = extremely; ghoram = dreadful; viśvāmitraḥ = Viśvāmitra; mahat = and great; tapaḥ = austerity.
O Rāghava, remembering his humiliation with a burning heart and having become an enemy of the great soul Vasiṣṭha, Viśvāmitra sighed repeatedly, departed to the south with his queen and performed extremely dreadful and great austerity.
By showing that all of the weapons and the confidential mantras [to be used to activate those weapons] bestowed by Lord Śiva were rendered useless, it is established that he is not the Supreme Being. Now, the topic alluded to in the previous chapter—attaining the nature of a brāhmaṇa—is shown in nine chapters to be extremely difficult to attain.
In this chapter, the author points out that Viśvāmitra had the required potency to give shelter to Triśaṅku.
The root cause of the destruction of Viśvāmitra’s penances was his hostile attitude towards the great soul Vasiṣṭha. After all, an offense towards a person who has realized the Supreme Lord destroys all auspiciousness. Viśvāmitra departed to the south, to Śarāvatī, with his queen. This indicates that he would perform fire sacrifices that are appropriate for gṛhasthas.
NOTE. Why did Viśvāmitra offend the great soul Vasiṣṭha? Because he was in the mode of passion. Śrīla Prabhupāda explains, “One has to raise himself at least to the mode of goodness before the path to understanding the Supreme Lord can be opened. Without raising oneself to the standard of the mode of goodness, one remains in ignorance and passion, which are the cause of demoniac life. Those in the modes of passion and ignorance deride the scriptures, deride the holy man, and deride the proper understanding of the Supreme Personality of Godhead.” (Bhagavad-gītā 16.24 purport)