Srimad-Bhagavatam: Canto 6 - Chapter 1 - Verse 23


मघवन् द्विषत: पश्य प्रक्षीणान् गुर्वतिक्रमात् ।सम्प्रत्युपचितान् भूय: काव्यमाराध्य भक्तित: ।आददीरन्निलयनं ममापि भृगुदेवता: ॥ २३ ॥


maghavan dviṣataḥ paśyaprakṣīṇān gurv-atikramātsampraty upacitān bhūyaḥkāvyam ārādhya bhaktitaḥādadīran nilayanaṁmamāpi bhṛgu-devatāḥ


O Indra, your enemies, the demons, were extremely weak because of their disrespect toward Śukrācārya, but since they have now worshiped Śukrācārya with great devotion, they have again become powerful. By their devotion to Śukrācārya, they have increased their strength so much that now they are even able to easily seize my abode from me.


Lord Brahmā wanted to point out to the demigods that by the strength of the guru one can become most powerful within this world, and by the displeasure of the guru one can lose everything. This is confirmed by the song of Viśvanātha Cakravartī Ṭhākura: “By the mercy of the spiritual master one is benedicted by the mercy of Kṛṣṇa. Without the grace of the spiritual master, one cannot make any advancement.” Although the demons are insignificant in comparison to Lord Brahmā, because of the strength of their guru they were so powerful that they could even seize Brahmaloka from Lord Brahmā. We therefore pray to the spiritual master: By the mercy of the guru, even a dumb man can become the greatest orator, and even a lame man can cross mountains. As advised by Lord Brahmā, one should remember this śāstric injunction if one desires success in his life.